Theresa May faces a resignation showdown with Conservative MPs, who are poised to urge her to set out a clear timescale for her departure from Downing St.

The predicted move comes as MPs take control of the Brexit agenda to vote on a range of options aimed at breaking the deadlock.

On Wednesday evening, the Prime Minister is due to address the Tories’ 1922 backbench committee in the Commons when pressure will be applied for her to “name the date” by which she will leave.

“She should say she will be gone by the summer, so we can have a full leadership election and install the new leader in time for party conference in the autumn,” one backbencher told The Herald.

Some loyal supporters hope that a clear indication of her resignation timescale will encourage more colleagues to rally round and back her twice-rejected deal.

Nigel Evans, Joint Executive Secretary of the 1922, said he was encouraging Mrs May to “give the timetable for her departure”.

He pointed out how a number of Brexiteers wanted to make “absolutely certain she's nowhere near the negotiating table when we start talking about the future trade relationship with the EU”.

The Lancashire MP added: "If the Prime Minister announces a timetable of departure, that's going to swing a lot of people behind her deal; we could get it over the line."

It was suggested at last weekend’s informal Tory get-together at Chequers, aides to Mrs May sought to guage whether or not invited Brexiteers like Jacob Rees-Mogg, David Davis and Boris Johnson might be prepared to back her deal if she set out a clear timeline to her departure.

On Tuesday, following another marathon Cabinet meeting dominated by Brexit, the mood in Downing St began to lift after all three of those senior Brexiteers made positive noises about backing her deal.

Mr Rees-Mogg, Chairman of the Eurosceptic European Research Group, noted: “Perhaps the thought processes that people like me hadn’t gone through before is the thought that Brexit is a process rather than an event.” 

Mr Johnson last night warned there was now an "appreciable risk that we will not leave at all". 

Pointing to how MPs had now taken control of the Brexit process, raising the prospect of a softer Brexit or no Brexit at all, the former Foreign Secretary said: “If people like me are to support this deal, something I bitterly oppose, then we need to see the proof that the second phase of negotiations will be different from the first."

Mr Davis, calculated that Mrs May now had a "reasonable chance" of getting her deal through Parliament, noting: “It's not a good deal but the alternative is a complete cascade of chaos.”

Conservative sources again stressed she would only table a third meaningful vote if she is convinced she could win it.

To meet the requirements of the EU’s offer to extend exit day until May 22, Mrs May’s deal has to be agreed this week. A motion has to be passed 24 hours before the Commons debate and vote. As things stand, this means the Government would have to table it by close of play today for the debate and vote to take place on Thursday.

Friday is a non-sitting day but Government insiders have suggested the House could sit on that day to try to get the PM’s deal through to meet the EU’s conditions.

One senior figure pointed out the irony of passing Mrs May’s plan on the very day Britain was due to leave the EU: March 29.

The stumbling block for Mrs May continues to be the Democratic Unionists, which said having a yearlong extension was a “better strategy than volunteering to be locked into the prison of the withdrawal deal with the cell door key in the pocket of Michel Barnier”.

Meanwhile, there was still no clarity on whether Mrs May would allow a free vote on the “indicative votes” as she was warned she could lose another 20 ministers, including some in the Cabinet, if she did not.

Last night, the motions for debate today began to be tabled and included: 

*Labour’s for a comprehensive customs union with the EU with a UK “say” on future trade deals, a close alignment to the single market and a dynamic alignment on rights and protections;

*the so-called “Common Market 2.0” plan to enable continued participation in the single market and a "comprehensive customs arrangement";

*SNP MP Joanna Cherry’s proposal to require the Government to stage a vote on a no-deal Brexit two sitting days before the scheduled date of departure - if MPs refused to authorise no-deal, the PM would then be required to halt Brexit completely by revoking Article 50 and 

*a motion from Labour’s Margaret Beckett calling for a People's Vote and supported by the Independent Group of MPs.

*The SNP has also tabled an indicative motion to require the UK government to secure the consent of the Scottish Parliament and Welsh Assembly before it could take the UK out of the EU.

In a separate development, it was announced on Monday that MPs would debate an online petition calling for Brexit to be scrapped. It is now nearing six million signatures.

But the Government rejected it, saying: “This Government will not revoke Article 50. We will honour the result of the 2016 referendum and work with Parliament to deliver a deal that ensures we leave the European Union."