Jeremy Corbyn is coming under pressure to rule out Labour MPs abstaining in a crunch Brexit vote, after the minister in charge of EU withdrawal said defeat could kill off Theresa May’s plan altogether.

Supporters of a Final Say referendum have accused the Labour leader of offering a lifeline to the prime minister as she prepares her fourth attempt to force the plan through parliament.

Meanwhile, Ms May is expected to resist demands to set out a timetable for her departure as PM as she meets Tory grandees who have called for “clarity” on her intentions.

The PM will meet the executive of the backbench 1922 Committee on Thursday amid speculation that failure to name a date could prompt a rethink of their decision to block an early confidence vote among MPs.

Ms May has launched a last-ditch effort to ratify Brexit before the summer by bringing her Withdrawal Agreement Bill before parliament in the week beginning 3 June, whether or not she has secured the agreement with Labour that she needs to guarantee its safe passage.

Brexit billboards: Campaigners remind MPs of past promises Show all 15 1 /15 Brexit billboards: Campaigners remind MPs of past promises Brexit billboards: Campaigners remind MPs of past promises Nigel Farage has spent his political career campaigning for the UK to leave the EU. Twitter/Led By Donkeys Brexit billboards: Campaigners remind MPs of past promises Boris Johnson's support for Brexit took many by surprise before the EU referendum. Twitter/Led By Donkeys Brexit billboards: Campaigners remind MPs of past promises The UK and EU are yet to agree on a withdrawal deal. Twitter/Led By Donkeys Brexit billboards: Campaigners remind MPs of past promises This was taken from a 2012 speech delivered by Mr Davis. He does not currently support a second Brexit referendum. Twitter/Led By Donkeys Brexit billboards: Campaigners remind MPs of past promises Boris Johnson now supports a hard Brexit and resigned from the cabinet in 2018 over Theresa May's strategy. Twitter/Led By Donkeys Brexit billboards: Campaigners remind MPs of past promises The US recently issued trade negotiation objectives for future talks with the UK. The country made clear that it expects access to the UK's agriculture industry, reviving the debate about chlorinated chicken. Twitter/Led By Donkeys Brexit billboards: Campaigners remind MPs of past promises Nigel Farage does not support the current campaign for a second Brexit referendum. Twitter/Led By Donkeys Brexit billboards: Campaigners remind MPs of past promises Despite this quote, in February 2019 Boris Johnson said a no deal Brexit "may yet be the best option for the UK". Twitter/Led By Donkeys Brexit billboards: Campaigners remind MPs of past promises The UK and EU are yet to begin negotiating a deal regarding their future relationship. Twitter/Led By Donkeys Brexit billboards: Campaigners remind MPs of past promises Theresa May announced that the UK would be leaving the Single Market in her Lancaster House speech in January 2017. Twitter/Led By Donkeys Brexit billboards: Campaigners remind MPs of past promises Theresa May triggered Article 50 on 29 March 2017. Her withdrawal deal is yet to be passed. Twitter/Led By Donkeys Brexit billboards: Campaigners remind MPs of past promises A classic from the 2015 general election campaign. David Cameron resigned on 24 June 2016, following the EU referendum result. Twitter/Led By Donkeys Brexit billboards: Campaigners remind MPs of past promises David Davis resigned from his post as Brexit secretary in July 2018 after disagreeing with Theresa May's negotiation strategy. Twitter/Led By Donkeys Brexit billboards: Campaigners remind MPs of past promises Michael Gove was one of the most influential Leave voices during the EU referendum campaign. Twitter/Led By Donkeys Brexit billboards: Campaigners remind MPs of past promises Jacob Rees-Mogg, a prominent backbencher, does not support a second Brexit referendum. He has called the use of this quote "fundamentally dishonest" as it was taken from a 2011 speech discussing the option of referendum before David Cameron entered negotiations with the EU. Such a vote was never held. Twitter/Led By Donkeys

After face-to-face talks between Mr Corbyn and Ms May, Labour said it would not support the bill without a compromise agreement complete with safeguards to avoid it being unpicked by a future Tory leader. “We are not in the business of getting into a car when we don’t know where it’s going,” said one source.

But senior Labour sources refused to rule out the party’s MPs being whipped to abstain in the crucial second reading vote, potentially saving the PM from defeat at the hands of Leave-backing Tory rebels and the DUP.

The move sparked a hostile response from backers of a second referendum, including one senior shadow cabinet minister who said he would ignore any instruction to abstain.

Edinburgh South MP Ian Murray said: “Labour must not issue a blank cheque to Theresa May over Brexit.

“Abstaining would be allowing a Tory Brexit to go ahead without even pressing for a People’s Vote and that would be totally unacceptable, so I hope the party leadership will make it clear that it’s just not on.”

Ian Murray warned abstention could usher in a Tory Brexit (PA)

Former Labour MP Chuka Umunna, chief spokesperson for Change UK, said: “By refusing to rule out abstaining on the second reading of the Withdrawal Agreement Bill, the Labour Party is offering Theresa May and her Brexit plan a lifeline. This is the clearest indication yet that the Labour leadership is working with the Tory government to deliver Brexit.”

Supporters of EU membership had been buoyed by Brexit Secretary Stephen Barclay’s admission that defeat for the WAB would be the final death knell for the deal laboriously negotiated over two years and agreed with the EU in November.

Mr Barclay told a parliamentary committee that if the bill falls “then the Barnier deal is dead in that form and I think the House will have to then address a much more fundamental question between whether it will pursue ... a no-deal option or whether it will revoke”.

Downing Street indicated that discussions will take place in the coming weeks not only with Mr Corbyn’s party but also with Tory backbenchers and the DUP, aiming to win “the broadest possible support” for the bill’s passage through the Commons. Asked whether Ms May would go ahead even if no such coalition can be assembled, a source said: “We are going to bring the bill forward in that week.”

Cross-party talks with Labour are continuing at official level, but no “plenary” meetings between ministers and their counterparts have been announced.

Ms May faces a tough challenge fitting an expected two-day second reading vote into a week when she will be busy with the three-day state visit of the US president, Donald Trump, and D-Day commemorations in Portsmouth and Normandy. Time is even tighter because parliament is not currently scheduled to sit on the Monday or Friday.

Aides shrugged off the timing issue, saying Number 10 was “fully aware” of the busy schedule. They declined to say whether the WAB would be published ahead of the Whitsun recess, beginning on 23 May, to give MPs time to digest the long and complex constitutional legislation.

Who could succeed Theresa May as Conservative leader? Show all 9 1 /9 Who could succeed Theresa May as Conservative leader? Who could succeed Theresa May as Conservative leader? Boris Johnson Former foreign secretary Boris Johnson has long been hopeful, he previously stood in the leadership contest that followed the Brexit vote and has at many times since been thought to be maneuvering himself towards the goal. He remains a darling of the party's right wing, particularly those in the ERG, and is the most popular choice among Tory voters but his leadership bid would be fiercely opposed by many MPs PA Who could succeed Theresa May as Conservative leader? Michael Gove Environment secretary Michael Gove is another member who has long wanted to be leader. He has lately been known for rousing his party in the commons, his recent speeches on the Brexit deal and Labour's no confidence motion have overshadowed the Prime Minister's. He has been loyal to the Prime Minister, partly to shed his reputation as a backstabber who abandoned Boris Johnson to stand against him in the 2016 leadership election Getty Who could succeed Theresa May as Conservative leader? Dominic Raab Former Brexit secretary Dominic Raab has emerged as a favourite to be the Brexiteer candidate in a contest to succeed to Ms May. He displayed a grip on detail in his role as Brexit secretary. When asked recently if he would like to become prime minister he replied "never say never" Getty Who could succeed Theresa May as Conservative leader? Rory Stewart International development secretary Rory Stewart is pitching himself as the sensible candidate, promising to rule out both a second referendum and a no-deal Brexit. He was only recently promoted to the cabinet, previously serving as prisons minister, where he caught headlines with a pledge to resign if he could not reduce levels of violence within a year PA Who could succeed Theresa May as Conservative leader? Esther McVey The former work and pensions secretary announced that she will be standing for the leadership when May leaves. McVey is the first to explicitly state that she intends to stand. She resigned from the cabinet in protest over May's Brexit deal AFP/Getty Who could succeed Theresa May as Conservative leader? Sajid Javid Home secretary Sajid Javid is said to have a plan in place for a leadership race. He made headlines over Christmas when he declared that people smuggling over the English channel was a "major incident" and more recently when he revoked the citizenship of ISIS bride Shamima Begum. Son of a bus driver, he wants the Conservatives to be seen as the party of social mobility PA Who could succeed Theresa May as Conservative leader? Jeremy Hunt Foreign secretary Jeremy Hunt was recently thought to be the favourite in the event of a leadership race as he could sell himself as the man to unite the party. Critics worry that his long stint as health secretary could return to haunt him at a general election. He has reportedly been holding meetings with Tory MPs over breakfast to promote his leadership PA Who could succeed Theresa May as Conservative leader? Andrea Leadsom Following the Prime Minister's second defeat over her Brexit deal, Leader of the house Andrea Leadsom hosted a dinner party at which "leadership was the only topic of conversation", The Times heard. Leadsom ran against Theresa May in the 2016 leadership election before dropping out, allowing May to become Prime Minister AFP/Getty Who could succeed Theresa May as Conservative leader? Priti Patel Former international development secretary Priti Patel is thought to be positioning herself as a contender. One MP told The Independent "she knows she's from the right of the party, the part which is going to choose the next leader, so she's reminding everyone she's there." Patel left the government late in 2017 after it emerged that she had held undisclosed meetings with Israeli officials PA

At Prime Minister’s Questions in the Commons, Ms May faced another call for her resignation from one of her own backbenchers.

Peter Bone told her that “loyal and dedicated” activists in his Wellingborough constituency had given him a clear message to deliver to her.

“They say that her deal is worse than staying in the EU, that they want us to come out now on a no-deal basis, and third, more importantly, they’ve lost confidence in the prime minister and wish her to resign before the European elections,” he said.