MPs are trying to influence the Brexit process in a number of ways, as Theresa May continues her bid to get the EU to change the deal.
The prime minister has asked MPs to approve a motion on Thursday simply acknowledging that process is ongoing and restating their support for the approach.
Several MPs tabled amendments setting out alternative plans and Commons Speaker John Bercow has selected three to be put to a Commons vote.
Even if they won the backing of a majority of MPs, the proposals would not be binding on the government. However, they could put pressure on Mrs May to change course.
She has adopted proposals from two successful backbench amendments tabled in January.
One asked her to seek alternatives to the “backstop”, which aims to prevent the return of customs checkpoints on the Irish border in the event that no trade deal has come into force. The other rejected leaving the EU without a formal exit deal.
The selected proposals are below. Use our guide to Brexit jargon or follow the links for further explanation.
Labour frontbench amendment
Requires the government to either give MPs a vote on the withdrawal agreement and political declaration on future UK-EU relations by 27 February, or make a statement saying there is no longer an agreement in principle with Brussels and so allow MPs to vote on – and amend – its planned next steps.
Labour Leader Jeremy Corbyn’s amendments are considered unlikely to receive the necessary backing from Conservative backbenchers to succeed.
Liberal Democrat leader Sir Vince Cable has tabled a bid to change the wording of this amendment to delay the Brexit date to allow for a referendum on the deal, with the option to remain in the EU.
The SNP’s Westminster leader Ian Blackford, centre, tabled the amendment on behalf of his party
Seeks to postpone the Brexit date by at least three months.
This has the backing of Liberal Democrats, as well as the SNP contingent.
Conservative backbencher Anna Soubry’s amendment
Instructs the government to publish within seven days “the most recent official briefing document relating to business and trade on the implications of a no-deal Brexit presented to cabinet”.
This has the backing of some mostly Remain-supporting Labour and Conservative backbenchers.
Does the government motion face defeat?
The government may well fight off these attempts to amend its motion.
But even if it does, it is not guaranteed to win the subsequent vote. Some Conservative Brexiteers in the European Research Group (ERG) have indicated they will refuse to back the government.
They are angry because the motion not only supports the view backed by a majority of MPs last month that the government should seek an alternative to the “backstop”, but also a separate move to stop Brexit happening without a formal deal, which the Commons supported at the same time.
Most MPs want to avoid a no-deal scenario, fearing chaos at ports and disruption to business. However, some Brexiteers have played down that prospect, arguing it is an example of “Project Fear”, and say the no-deal option offers leverage in negotiations with Brussels.
MPs are to debate and vote on the next steps in the Brexit process later, as Theresa May continues to try to get a deal through Parliament.
A series of amendments – designed to change the direction of Brexit – will be considered in the debate, which is expected to be a routine procedure.
But BBC political editor Laura Kuenssberg said the PM could be facing another defeat.
Some Tory Brexiteers are refusing to back the government, she said.
No 10 insists Mrs May still plans to hold a vote on a deal as soon as possible but Labour has accused her of “running down the clock” in an effort to “blackmail” MPs into backing her deal.
The prime minister has asked MPs to approve a motion simply acknowledging that the process was ongoing and restating their support for the approach.
But several MPs have tabled amendments – which set out alternative plans – including one from Labour that would force the government to come back to Parliament by the end of the month to hold a substantive Commons vote on its Brexit plan.
Another, from the SNP, calls on the government to pass a law leading to the Brexit process being halted.
Commons Speaker John Bercow is yet to decide which of these will actually be considered by MPs.
However, influential Brexiteers from the European Research Group of Tory backbenchers are angry at being asked to support the PM’s motion.
This is because it combines the view backed by a majority of MPs last month that the government should seek an alternative to the “backstop” with a separate move to stop Brexit happening without a formal deal.
The backstop aims to prevent the return of customs checkpoints on the Irish border in the event that no trade deal comes into force.
The group’s deputy chairman, Mark Francois, told the BBC: “We cannot vote for this as it is currently configured because it rules out no deal and removes our negotiating leverage in Brussels.”
He said members had “pleaded” with Downing Street to change the wording, which he said goes back on what the prime minister has previously told MPs.
“A senior ERG source says they haven’t decided whether to abstain or vote against, but they won’t back the government,” said BBC political editor Laura Kuenssberg.
Most MPs want to avoid a no-deal scenario, fearing chaos at ports and disruption to business. But some Brexiteers have played down that prospect, arguing it is an example of “Project Fear”.
MPs rejected the deal negotiated with the EU by a historic margin in January and the prime minister says she is seeking legally-binding changes to the controversial “backstop” – the “insurance policy” aimed at avoiding a return to border checks between Northern Ireland and the Irish Republic.
The UK is currently due to leave the EU on 29 March, whether or not a deal has been approved by the Commons.
Could Brexit cause a Labour split?
By BBC political editor Laura Kuenssberg
You’ll be used to people in my kind of job saying things like, “these are critical days”.
And hands up, on many of the occasions when a big move is predicted, a damp squib often comes along to squelch the expectation.
What I’m about to say may well be a repetition of that familiar phenomenon. But I’m not the only person in Westminster this week to be wondering whether after many, many, many months of private conversations where this possibility was discussed, in the next couple of weeks, maybe even in the next couple of days, something that actually is critical is going to start happening.
The prime minister has promised to return to the Commons on 26 February with a further statement – triggering another debate and votes the following day – if a deal has not been secured by that date.
If a deal is agreed, MPs will have a second “meaningful vote”, more than a month after Mrs May’s deal was rejected in the first one.
Mrs May told MPs on Tuesday she was discussing a number of options with the EU to secure legally binding changes to the backstop, including replacing it with “alternative arrangements”, putting a time limit on how long it can stay in place, or a unilateral exit clause so the UK can leave it at a time of its choosing.
The EU has continued to say it will not renegotiate the withdrawal agreement.
On Wednesday, European Council President Donald Tusk tweeted that “no news is not always good news”, saying the EU was “still waiting for concrete, realistic proposals from London”.
The prime minister has also said she will lift the requirement for a 21-day period before any vote to approve an international treaty, which means she could delay the final Brexit vote until days before the UK is due to leave the EU.
Former attorney general Dominic Grieve warned on Tuesday that time was running short for the ratification of a deal under the Constitutional Reform and Governance Act.
The Act requires 21 sitting days before the ratification of any international treaty, to allow MPs to study the agreement.
But Mrs May responded: “In this instance MPs will already have debated and approved the agreement as part of the meaningful vote.”
If there was not time for normal procedures, the government would amend the law around Brexit to allow it to be ratified more quickly.
The Food Standards Agency’s advice is that some species of mould can produce toxins, and that food that is obviously rotten or containing mould should not be eaten. Children, elderly people and pregnant women, along with others who have a weakened immune system, should be especially careful, the FSA advises.
It adds that while removing the mould – along with significant amount of the surrounding product – may work, there is no guarantee it would remove all unseen toxins.
But Hugh Pennington, professor of bacteriology at Aberdeen University, told BBC Radio 4’s PM programme that he would scrape the mould off, “depending on the quality of the jam”.
“Generally speaking, I wouldn’t be worried about the mould doing any harm,” he said. “I would just question how long it has been in the cupboard, but it’s safe to eat.”
“Jam’s got a lot of sugar in it, which stops nasty bugs getting in it. It’s been made by boiling… so it’s a pretty safe product.”
Theresa May went head-to-head with Jeremy Corbyn in the House of Commons. Here’s what happened.
Jeremy Corbyn threw the prime minister a Brexit curveball at this session.
Most observers were expecting the PM to get a grilling over reported comments by her chief Brexit adviser Olly Robbins – but the Labour leader went after Transport Secretary Chris Grayling instead.
He focused all six of his questions on the “fiasco” of the Seaborne Freight contract.
The ferry company with “no ships and no trading history” has had its contract to provide services in the event of a no-deal Brexit cancelled.
Mr Corbyn said this was symbolic of the government’s “costly, shambolic and evasive” handling of Brexit. “What went wrong?,” he asked the prime minister.
Mrs May said 90% of the ferry contracts awarded in case of a no-deal Brexit scenario, went to DFDS and Brittany Ferries.
“Due diligence was carried out on all of these contracts,” she told the Labour leader.
The transport secretary had told MPs the decision to award a contract to Seaborne Freight “had no cost to the taxpayer”, said Mr Corbyn, but the National Audit Office found that £800,000 had been spent on external consultants to assess the bid. Could the prime minister “correct the record”?
Mrs May said Mr Corbyn was “late to the party” because she had been asked about this yesterday by the SNP. “Labour following the SNP, well whatever next,” sniped the PM before repeating her line about “proper due diligence”.
Mr Corbyn said Freedom of Information requests showed Chris Grayling had “bypassed” the rules which allow normal scrutiny of a deal.
Mrs May said the Seaborne Freight contract had been handed out following individual assessments by consultants, and no money had been paid to Seaborne Freight.
It was “entirely right and proper” to make sure that the government was preparing for any no-deal Brexit, she added.
Mr Corbyn said taxpayers were facing a £1m legal bill for contesting Eurotunnel’s court case against the government over its “secretive and flawed” no-deal transport contracts process.
Not only that, he told MPs, Thanet Council, in Kent, was facing a £2m budget deficit as a result of the Seaborne Freight debacle. Could the PM offer “cast iron guarantees” that the people of Thanet would not be hit with this bill?
Mrs May said Department of Transport officials were “in discussions” with Thanet council. The ferry contracts were about safeguarding medical supplies in the event of a no-deal Brexit, she added.
Mr Corbyn said the prime minister should follow the advice of the House and take no deal off the table and “negotiate seriously with the EU”.
He broadened out his attack on Chris Grayling, for “ignoring warnings” about drones at airports, ignoring warnings about the collapse of outsourcing giant Carillion, overseeing the “disastrous” new rail time tables, and rail fare increases.
And now, said Mr Corbyn, Mr Grayling was in charge of a “vital aspect of Brexit planning”. “How on earth” could the prime minister have any confidence in him?
Mrs May replied that rail investment was at its highest since the Victorian era and that was 20% higher every year on average than under Labour.
She had clearly come armed with attack lines for Mr Corbyn over his Brexit strategy, so she unloaded them all as their exchange came to an end, accusing the Labour leader of “ambiguity” and “playing politics” and of failing to say whether he wanted Brexit, or a second referendum.
People no longer say he is a “conviction politician”, she concluded.
What else came up?
The SNP’s leader at Westminster Ian Blackford said that with 44 days to go until Brexit, Mrs May must stop “playing fast and loose” with the economy.
Conservative backbencher Henry Smith gave the prime minister a chance to rebut the reported comments by Olly Robbins, who was overheard in a Brussels bar saying the EU was likely to allow an extension to the Brexit process.
Conservative MP George Freeman, a former adviser to Mrs May, asked whether those who had brought the system into disrepute “like Philip Green” should be stripped of their honour. Mrs May says there was an independent forfeiture committee.
Labour MP Rosie Cooper asked Theresa May about a Conservative election promise to keep the provision for those 75 and older.
Stop and search, when carried out the right way, is an “effective tool for our police forces”, Theresa May told Conservative MP Gareth Thomas, adding that officers must these powers “lawfully”.
Labour’s Steve McCabe reminded the PM of her call to end rip-off energy prices, telling her 2.5 million people were now in fuel poverty.
And finally, Jeremy Corbyn and Theresa May shared their memories of England’s victory in the 1966 World Cup final, as they paid tribute to legendary goalkeeper Gordon Banks, who died this week.
Here is BBC Parliamentary Correspondent Mark D’Arcy’s take
Both the main players at PMQs had one of their better days, proving, I suppose, that it’s not a zero-sum game, where one of them must do badly for the other to do well.
Jeremy Corbyn continued Labour’s recent targetting of the Transport Secretary, Chris Grayling, with a series of detailed questions about the Seabourne Ferries saga.
It was an old school piece of PMQs questioning, building up an attack over a series of questions, which saw the PM digging into her file for the pre-scripted answers.
She, in turn, was at her most effective when she counter-attacked on Labour’s policy ambiguity over Brexit, with a particularly wounding line that Jeremy Corbyn was losing his reputation as a conviction politician.
It was also notable that the Conservative benches were rather muted during the attacks on their transport secretary. Perhaps the accumulated weight of the railway timetables saga, the Gatwick drones and even his policies as justice secretary have depressed backbench support? So maybe the attack was a tactical success for Mr Corbyn, but was it also a strategic missed opportunity?
Brexiteer Tories rather tiptoed around the reported remarks of the PM’s Brexit advisor, Olly Robbins, overheard in a Brussels bar. But the twin suggestions attributed to him, of a postponement of Brexit day and of the Northern Ireland backstop being a “bridge” to a post-Brexit customs union with the EU, cause them deep alarm.
Mr Corbyn did not seek to deepen it further, even though it would have been quite easy to segue from Grayling to Robbins, and it was left to the SNP’s Ian Blackford and later the Conservative Henry Smith, to target the alleged bar-room indiscretion.
The PM’s elegant prepared response: “What someone said to someone else, overheard by someone else…in a bar” was eventually deployed in answer to Mr Smith, but was probably drafted with Mr Corbyn in mind.
The other big PMQs player, John Bercow, had a quiet time. His rebukes were genial, even jovial, and no-one was bruised by them. He even indulged a few spurious points of order at the end, although I’m not sure how grateful Ian Blackford will have been for his colleague Mharie Black’s complaint that when her leader rose to ask his question, lots of MPs immediately got up and left the Chamber.
Elsewhere, there were interesting responses to well placed questions from Tories Robert Halfon (on school exclusions) and George Freeman (Sir Philip Greene’s knighthood) and to Labour’s Chris Evans (on suicide and self harm images on social media) with the PM keen to demonstrate that her government is not so fixated on Brexit that it can’t deal with other issues.
Speaking at a Politico event, shadow chancellor John McDonnell called Churchill a “villain”
John McDonnell has branded Sir Winston Churchill a “villain” over his role in dealing with striking miners in 1910.
Speaking at a Politico event and when asked whether Churchill was a hero or villain, the shadow chancellor replied: “Tonypandy – villain”.
During the Tonypandy riots of 1910, troops were sent out to control striking miners who wrecked town centre shops and mine-owners’ property.
Churchill was voted the greatest Briton in a BBC poll in 2002.
In response to Mr McDonnell’s comments, Labour MP Ian Austin posted a picture of the wartime leader on social media.
He tweeted: “Look who takes pride of place on my mantelpiece in Dudley: a real British hero, the greatest ever Briton, the man who motivated Britain to defeat the Nazis and fight not just for our liberty but the world’s freedom.”
Health Secretary Matt Hancock tweeted that Churchill “was one of the greatest ever to have lived”.
The Tonypandy riots took place on the evenings of 7 and 8 November 1910 and involved violent clashes between striking miners and the police, with soldiers arriving on the second day.
One miner was killed.
The incident haunted Churchill for the rest of his career and many of his critics saw it as an anti-trade union stance.
The Scottish government has stepped up its preparations for a no-deal Brexit as it again called on Theresa May to rule out the possibility.
First Minister Nicola Sturgeon said she still believes no deal can be avoided.
But she said her government had a duty to plan for the possibility as best it could.
The UK is due to leave the EU on 29 March, but MPs have so far refused to back the deal agreed by the prime minister and the EU.
ITV News has said that one of its reporters overheard the UK’s chief Brexit negotiator, Olly Robbins, saying in a Brussels bar that the EU was likely to allow an extension to the Brexit process.
Mrs May has played down reports that she could force MPs to choose between backing her deal or accepting a delay to EU withdrawal.
The prime minister told the Commons that people should not rely on “what someone said to someone else, as overheard by someone else, in a bar”.
She insisted that the government still intends to leave the EU on 29 March with a deal in place – but Downing Street has stressed that the possibility of a no-deal Brexit “remains on the table”, saying it is an “eventuality we wish to avoid, but one we continue to plan for”.
The UK government argues that the best way to avoid no deal is for MPs to back the prime minister’s proposals, which it says are “the best deal available for jobs and the economy across the whole of the UK, allowing us to honour the referendum and realise the opportunities of Brexit.”
Speaking after a meeting of the Scottish cabinet in Glasgow, Ms Sturgeon told BBC Scotland that Mrs May was attempting to “run down the clock” in an attempt to “blackmail” MPs into backing her deal “at the very, very last minute”.
She added: “The prime minister can only get away with that if the House of Commons allows her to get away with that, and the longer it does the more complicit it will become in the disaster that eventually unfolds”.
Scotland’s chief economist warned that a no-deal Brexit would lead to a “major dislocation” to the country’s economy in his latestState of the Economy report , which was published on Wednesday morning.
Gary Gillespie said disruptions to logistics, supply, trade, investment, migration and market confidence could cause a “significant structural change in the economy”.
‘Reckless and negligent’
Ms Sturgeon said it was “reckless and negligent” for the UK government to refuse to rule out no-deal, adding: “But we appear to be dealing with a UK government that’s prepared to act recklessly and negligently.
“Therefore as of today we have stepped up our no-deal planning. We don’t think it should be inevitable, we’ll do everything in our power to help rule that out.
“But we would not be doing our job properly if we didn’t properly plan as best we can, because not all of the consequences will be able to be mitigated.”
MPs rejected the deal negotiated between the UK and the EU by a historic margin in January, and the prime minister saying she is now seeking legally-binding changes to the controversial “backstop” – the “insurance policy” aimed at avoiding a return to border checks between Northern Ireland and the Irish Republic.
In her BBC Scotland interview, Ms Sturgeon also repeated that she would set out her thinking on the timing of a second independence referendum in the “coming weeks”.
When asked whether she believes Scotland will be independent in the next few years, she replied: “I’m not going to put a precise timescale on it, but I do hope and believe that Scotland will become independent.
“I hope that’s within the next few years because I think it becomes more and more urgent that we are in charge of the big decisions that shape our future and shape our destiny.”
Opposition Leader Jeremy Corbyn says the “country facing biggest crisis in a generation” and Ms May is “recklessly running down the clock”. The prime minister has “more excuses and more delays”, he adds. The Labour leader asks what progress Mrs May has made on alternative arrangements and if she set those arrangement before the House. Jemery Corbyn accuses the prime minister of “playing” with jobs and industries, adding that the Nissan decision may be the “thin end of a very long wedge”.
He adds that the Leader of the House says a meaningful vote will be on 21 March, days before Brexit, and asks if this is not the case when will the meaning vote be.
Mr Corbyn says the prime minister is “playing chicken with people’s livelihoods”.
MPs will get another chance to vote on Brexit this month – even if Theresa May has not been able to negotiate a deal by then.
Housing Secretary James Brokenshire admitted it might not be the final, decisive vote on the PM’s deal that Labour and some Tories are demanding.
The prime minister needs to get a deal approved by Parliament by 29 March to avoid a no-deal Brexit.
Labour has accused her of “cynically” running down the clock.
Instead of a “meaningful” vote on the prime minister’s deal with the EU, MPs could be given another series of non-binding votes on possible Brexit alternatives by 27 February, with the final vote on whether to approve or reject the deal delayed until the following month.
On Wednesday, Mrs May will ask MPs for more time to get legally-binding changes to the controversial Northern Irish backstop, which she believes will be enough to secure a majority in Parliament for her deal.
But the following day, Labour will attempt to force the government to hold the final, “meaningful vote” on Mrs May’s Brexit deal by 26 February.
Mr Brokenshire refused to commit to this date in an interview with the BBC’s Andrew Marr Show, saying there could be more votes on amendments to the proposed deal instead.
“If the meaningful vote has not happened, so in other words things have not concluded, then Parliament would have that further opportunity by no later than 27 February,” said Mr Brokenshire.
“I think that gives that sense of timetable, clarity and purpose on what we are doing with the EU – taking that work forward and our determination to get a deal – but equally knowing that role that Parliament very firmly has.”
He also ruled out removing the Irish backstop from the government’s deal with the EU, as some Conservative MPs are demanding.
He said ministers were exploring a possible time-limit to the backstop, or a legal mechanism allowing the UK to exit the backstop without the agreement of the EU, but he insisted some kind of “insurance policy” was needed to keep the Irish border free-flowing.
But Labour’s shadow Brexit secretary, Sir Keir Starmer, says he believes the prime minister is “pretending to make progress” on the Irish backstop issue.
He says what she actually intends to do is return to Parliament after the 21/22 March European Council summit the week before Brexit and offer MPs a “binary choice” – her deal or no deal.
“There needs to be a day when Parliament says that’s it, enough is enough.”
Lib Dem leader Sir Vince Cable said delaying the final vote on the Brexit deal was “worse than irresponsible” and he “would not be surprised if [Theresa May] faces a massive rebellion by Conservative MPs”.
Conservative MP Sarah Wollaston, who like Sir Vince has campaigned for another EU referendum, called for ministers who were “serious” about preventing a no-deal Brexit to resign and vote against the government.
Fellow Conservative MP Heidi Allen also called for ministerial resignations, saying it was “completely irresponsible” for the government to keep delaying the final Brexit vote.
Labour is proposing its own Brexit plan, which would involve the UK staying in a customs union with the EU, which they say could get the backing of a majority of MPs.
The government has not ruled out supporting this – and has promised a formal response to it and further talks with Labour – but they say it would prevent the UK from making its own trade deals after Brexit.
There are fewer than 50 days until Brexit. The law is already in place which means the UK will leave the EU on 29 March 2019.
Mrs May’s Brexit deal – which she spent months negotiating and had agreed with the EU – covers the terms of the UK’s divorce and the framework of future relations.
But it was rejected by the UK Parliament and if it is not approved by Brexit day, the default position would be a no-deal Brexit.
Last month, Parliament voted in favour of an amendment that supported most of the PM’s deal but called for backstop which is a last-resort option to prevent a hard border in Ireland – to be replaced with “alternative arrangements”. The prime minister is now in talks with Brussels to seek these changes to the backstop.
A number of government ministers will also be meeting their counterparts across the continent this week, in order to underline Mrs May’s determination to achieve a deal.
Critics of the backstop in Mrs May’s current deal say they could tie the UK to EU rules indefinitely or mean Northern Ireland ends up under a different system to the rest of the UK.
But the Irish government and the EU have repeatedly rejected calls for changes.
Other options likely to be debated by MPs on Thursday include extending Article 50 the legal mechanism taking the UK out of the EU on 29 March, to allow more time to reach an agreement with Brussels.
The prime minister has met Leo Varadkar in Dublin for talks focused on Brexit and the political deadlock in Northern Ireland.
Theresa May has now returned to the UK after having dinner with the taoiseach (Irish prime minister).
The talks in Farmleigh House lasted about two hours.
The meeting took place after Mr Varadkar met Northern Ireland’s main political parties in Belfast on Friday.
Mrs May was accompanied in Dublin by the UK’s Brexit negotiator Olly Robbins and her chief of staff Gavin Barwell.
The Irish government said the two leaders discussed “the latest Brexit developments” as well as the “ongoing political impasse in Northern Ireland”.
The meeting comes after the EU said it will hold more talks with the UK to help the prime minister get a Brexit deal through the Commons.
Earlier, Attorney General Geoffrey Cox met his Irish counterpart after travelling to Dublin for talks.
Speaking in Belfast, Mr Varadkar said it was “not a day for negotiations” but it was an opportunity to “share perspectives”.
He added that he was looking to restore confidence and trust with the prime minister during their meeting on Friday night.
Analysis: Diplomacy over dauphinoise potatoes
By Jayne McCormack, BBC News NI political reporter
A Friday night in Dublin for Theresa May as she continues trying to find a way through for her Brexit deal.
The prime minister came face-to-face with her Irish counterpart over a fillet of beef with dauphinoise potatoes and green beans.
It’s been a diplomatic whirlwind of a week as Mr Varadkar and Mrs May have bounced from Belfast to Brussels, both seeking backing for their respective positions.
It seems certain that the House of Commons will not pass any Brexit deal that includes the current backstop.
But the Irish government again today insisted it has to stay, with Mr Varadkar adding that he and the EU speak with one voice on this.
On Monday, UK-EU talks begin (again) in Brussels – but there’s no sign of a compromise coming down the tracks.
Several cabinet ministers have told the BBC a no-deal Brexit could lead to a vote on Irish unification.
But Democratic Unionist Party (DUP) leader Arlene Foster poured cold water on the prospect, saying that the 1998 Good Friday Agreement sets out “criteria for a border poll, and it hasn’t been met – therefore it will not be called”.
What is the current Brexit state-of-play?
On Thursday, Mrs May met EU leaders in Brussels in a bid to secure changes to the Irish border backstop in the Brexit agreement.
European Commission President Jean-Claude Juncker ruled out legally-binding changes to the backstop clause in the 585-page withdrawal document.
But he said the EU would be open to adding words to the non-binding future relations document that goes with the withdrawal agreement.
Other officials, including European Parliament Brexit co-ordinator Guy Verhofstadt, have said the backstop is “non-negotiable”.
On Wednesday, Mr Varadkar held meetings with top EU officials about the backstop and Ireland’s plans for a no-deal outcome.
He said that while he was “open to further discussions” with the UK government about post-Brexit relations, the legally-binding withdrawal agreement remained “the best deal possible”.
Speaking in Belfast, Mr Varadkar said “time is running out” to agree a deal, but that work needed to continue in order to ensure agreement was reached.
“When it comes to Brexit this is a negotiation that has the UK on one side and EU on the other,” he said.
“Any negotiation can only happen with Ireland and the EU working together.”
Where are we with the backstop?
It is the insurance policy to maintain an open border between Northern Ireland and the Republic of Ireland unless and until another solution is found.
The UK and EU made a commitment to avoid physical barriers or checks on the border, if no UK-EU trade deal is agreed before the Brexit transition period ends.
Many people are concerned that the return of such checks would put the peace process at risk.
But there has been opposition to the backstop from the DUP and Brexiteer MPs, who believe its terms could keep the UK tied to EU rules in the long term.
Last month, MPs backed an amendment in Parliament calling for “alternative arrangements” to replace the backstop.
A group of Conservative MPs has held talks aimed at finding other Brexit options that would avoid a hard border.
How did Northern Ireland parties react to Leo Varadkar’s visit?
The taoiseach travelled to Belfast to discuss the “ongoing political impasse”, the Irish government said.
Northern Ireland has been without a devolved government for more than two years.
Mr Varadkar, whose trip came days after Theresa May met the parties at Stormont to discuss her bid to make changes to the withdrawal agreement said he travelled north to “hear the perspective of the main parties”.
DUP leader Arlene Foster said her party had a “wide-ranging” discussion with the taoiseach.
Mrs Foster also said some people were engaging in “project fear” with the Brexit negotiations.
The party’s deputy leader, Nigel Dodds, said the backstop “is the problem”, but would not specify which possible alternative his party is supporting.
Sinn Féin’s vice-president Michelle O’Neill said her party would “hold the taoiseach’s feet to the fire” when it comes to defending the backstop.
She said he had given her an assurance he would remain firm with his stance.
The party also said they have been calling repeatedly for a border poll, and that they had urged Mr Varadkar to begin planning for one.
The Ulster Unionist Party’s (UUP) Brexit spokesperson Steve Aiken said there needed to be “level-headed conversations” and that the UUP had told the taoiseach how concerned they are by the terms of the Irish border backstop.
The UUP said it is working on a number of alternative proposals it wants the UK and EU to consider.
Alliance Party leader Naomi Long said they had a very constructive and wide-ranging discussion with Mr Varadkar.
“It’s fairly clear those this week suggesting there is some chance of the UK and Irish government doing a side deal without the EU are chasing after a no-way scenario,” she said.
SDLP leader Colum Eastwood said that it had been a “good meeting” and added that he and the taoiseach are “on the same side of this argument”.
“We have been watching with some dismay what has been going on in Westminster over the last couple of months,” he said.
“I don’t think anybody within the Irish government or the European Commission sees any opportunity for diluting the protection of citizens in Northern Ireland.”
What happens next?
Brexit Secretary Steve Barclay and EU negotiator Michel Barnier will hold talks in Strasbourg on Monday, as the EU and UK Brexit negotiating teams discuss proposed changes to the deal.
British sources say the talks will include discussion of the legally-binding withdrawal agreement, the BBC’s Brussels reporter Adam Fleming said.
An EU source said the further talks are an opportunity to listen to the UK’s ideas.
Mrs May and Mr Juncker will meet again before the end of February, to review progress.
The prime minister is expected to put the deal to a vote in the Commons towards the end of February.
She said the plan must change if it is to win the support of MPs who urged her to seek “alternative arrangements” to the backstop when rejecting the deal last month.
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Downing Street is expected to reply to Mr Corbyn’s letter later on Friday.
Home Secretary Sajid Javid told BBC Wiltshire it was “good that Jeremy Corbyn has finally started talking”.
But, he added: “In this letter he’s put five demands and I think any person reading that letter would know it’s far more about politics than it is about actually trying to work with the prime minister in the national interest”.
And Nigel Dodds, deputy leader of the Democratic Unionist Party – who Theresa May relies upon for votes in Parliament – said Mr Corbyn’s plan did not have the support of the Labour Party.
He added: “The way to a majority for a deal in the United Kingdom is with the Conservative Party and the DUP.
“I don’t believe Theresa May is going to split her party in order to reach out to Jeremy Corbyn, who is going to find it very difficult to bring his own party along, and he cant be relied upon to deliver the Brexit that the prime minister believes people voted for in the referendum.”
In contrast to Mrs May’s deal, Labour wants the UK to be a member of a customs union with the EU, with an agreement “that includes a UK say on future EU trade deals” and close ties to the single market.
Under Mrs May’s plan, the UK would leave the customs union, which she says would allow it to strike trade deals around the world.
A senior No 10 source said the government was looking at Labour’s proposals “with interest” but added: “There are obviously very considerable points of difference that exist between us.
“The PM continues to believe an independent trade policy is one of the key advantages of Brexit.”
The UK is due to leave the EU on 29 March when the two-year limit on withdrawal negotiations under the Article 50 process expires.
But Mrs May has been unable to get the withdrawal deal she has negotiated with the EU through Parliament – it was overwhelmingly rejected by MPs last month.
In Brussels on Thursday, she told EU leaders that she could get a “stable majority in Parliament” for the deal if they agreed to legally-binding changes to the Irish backstop clause – something they have always ruled out.
Talks are continuing with EU officials – but senior figures in Brussels gave a warm reception to Mr Corbyn’s alternative proposals.
The European Parliament’s chief Brexit negotiator Guy Verhofstadt said: “It’s important now that this leads to a position in the UK that has the broadest possible majority, so that we can conclude these negotiations.”
European Council President Donald Tusk also described Mr Corbyn’s letter as a “promising way” out of the impasse, according to an EU source.
Cabinet Office Minister David Lidington has said he is willing to discuss the proposals with Labour’s shadow Brexit Secretary Sir Keir Starmer.
Mr McDonnell told BBC Radio 4’s Today programme: “The prime minister has to accept that the only way she will get something through Parliament is a compromise like this.
“I think if Theresa May said ‘I will sign up to Labour’s deal’ and we went to Parliament, I think we would have a secure Parliamentary majority.”
Conservative MP Sir Oliver Letwin was among those suggesting Mr Corbyn’s move could open the way to a cross-party consensus, if Mrs May could not get her deal through:
But Labour’s position has upset some of the party’s own backbenchers who see it as facilitating a “Tory Brexit” that they say will harm their constituents.
Some Labour members of the People’s Vote campaign for another EU referendum have accused Mr Corbyn of abandoning his commitment at Labour’s conference to get behind a public vote if he can’t force a general election.
Owen Smith, who failed in his bid to topple Mr Corbyn in a 2016 leadership vote, has said he and “lots of other people” were considering their future in the party as a result.
Asked about Labour opposition to Mr Corbyn’s offer, Mr McDonnell said “not everyone’s going to get everything they want” and MPs would have to compromise in the long-term interests of the country – but denied it had effectively killed off the prospect of Labour backing another referendum.
He said people had “looked over the edge of a no-deal Brexit” and economic growth was already stalling: “Therefore now in the national interest we have got to come together and secure a compromise. If we can’t do that, well yes, we have to go back to the people.”
Other Labour backbenchers have welcomed Mr Corbyn’s move. Labour’s Stephen Kinnock, who backs the “Norway Plus” model of a close economic partnership with the EU, tweeted: “This can break the deadlock.”