A statement announcing the Prime Minister’s resignation could be just three weeks away if MPs defeat legislation to implement the UK’s exit from the European Union.
The announcement, following a lengthy meeting with backbench Tory representatives, came as Boris Johnson confirmed that he would seek the party leadership once Mrs May steps aside.
The Prime Minister agreed to meet Sir Graham Brady, the chairman of the backbench 1922 Committee, at the start of June following a vote on the Withdrawal Agreement Bill to set the details of a leadership contest.
“We have agreed to meet to decide the timetable for the election of a new leader of the Conservative Party as soon as the second reading has occurred and that will take place regardless of what the vote is on the second reading – whether it passes or whether it fails,”Sir Graham told reporters following a 90-minute meeting with Mrs May yesterday.
She was presented with an ultimatum by the executive of the 1922 after repeatedly resisting calls to set out a timetable to quit.
“It was a very frank discussion,” Sir Graham added. “I tried to make sure that all the views represented on the executive were expressed and we had a very frank exchange with the Prime Minister.”
Mrs May is facing a torrid two weeks leading up to her possible resignation, starting with European elections on 23 May which are likely to see the Conservatives crushed by Nigel Farage’s Brexit Party.
In the first week of June, the government faces a fourth vote on its Brexit plan when the Withdrawal Agreement Bill has its second reading in the Commons, with another defeat expected unless cross-party talks with Labour can reach a compromise.
The Prime Minister faces a difficult start to the month with the arrival of US president Donald Trump for a controversial state visit.
And on 6 June, a by-election in Peterborough could give the Brexit Party the chance of seizing a seat at Westminster and confirming the Tories’ slump. However, by securing a reprieve from Tory MPs until the start of June, Mrs May has ensured she will surpass Gordon Brown’s two years and 319 days in office.
A No 10 source acknowledged that if the Withdrawal Agreement Bill is defeated, the pressure for Mrs May to go immediately will ratchet up.
“She would have to say, ‘This is how I envisage the timetable for a leadership election happening and there would have to be some sort of agreement about that’,” the source said.
While the Prime Minister was meeting the 1922 Committee executive at Westminster, Mr Johnson announced he would join the race to succeed her.
“I’m going to go for it. Of course I’m going to go for it,” the former foreign secretary told a business event in Manchester.
Mr Johnson is the favourite to win a ballot of Conservative Party members if he can remain in the race through successive ballots of Tory MPs, who will whittle what is expected to be a large field down to a final pair of candidates.
Senior Scottish Conservatives have pledged to oppose Mr Johnson’s leadership bid, believing it will alienate Scots and harm Ruth Davidson’s chances of winning power at Holyrood.
Sources revealed at last year’s Conservative conference that they have organised what is being called “Operation Arse” to convince fellow Tories not to support him.
Responding to Mr Johnson’s announcement, Scottish Liberal Democrat MSP Alex Cole-Hamilton said: “Boris Johnson was the most incompetent foreign secretary in decades.
“Britain faces so many questions at this moment in history; the answer to none of them is Boris Johnson. Even the Scottish Conservatives have banned him from Scotland so as Prime Minister of the United Kingdom he will be a fat load of use.”
Mounting speculation about the Prime Minister’s imminent departure has seen Tory MPs Rory Stewart, Andrea Leadsom and Esther McVey already declare their candidacies to replace her.
A series of high-profile media appearances recently from Jeremy Hunt, Michael Gove and Dominic Raab have also buoyed speculation that they will run.
Mr Gove is believed to have the support of a number of Scottish Tories, as well as the backing of dozens of other colleagues in the Commons.
Mrs May’s decision to bring forward the Withdrawal Agreement Bill at the start of June was seen as a last throw of the dice to secure a political legacy by getting her deal through Parliament and taking Britain out of the EU before her time in office is finally up.
The Prime Minister has said it is “imperative” the government gets the legislation on to the statute book by the time MPs break for their summer recess – expected in late July.
However, while talks with Labour on a possible compromise agreement are continuing, it remains far from clear that she has the parliamentary numbers to get it through.
One possible hope for Mrs May would be if Labour ordered its MPs to abstain rather than vote against it.
However, the party leadership appears to be split on what course to take.
On Wednesday, shadow foreign secretary Emily Thornberry said Labour would oppose the bill.
However, yesterday, Jeremy Corbyn stopped short of saying they would vote against, saying only they “won’t support it” unless it met their demands.
“We’ve put to the government a very strong position that we want a customs union with the European Union to protect jobs and trade, as well as trade access, and we want to protect the rights at work, consumer rights and environmental rights,” he said. “Our view is there has to be a relationship with Europe which guarantees those things and if that bill doesn’t do it then we won’t support it.”
Meanwhile, Nicola Sturgeon will launch the SNP’s manifesto for next week’s European election in Glasgow today, arguing that a vote for the Nationalists is the best way to stop Brexit.
“There is now a real chance to keep Scotland in the European Union,” Ms Sturgeon will say, calling on voters to send the Prime Minister a “strong, resolute message” to “stop ignoring Scotland”.
“This is an election the Tories never wanted. They wanted Scotland to be out of the EU by now.
“They’ve ignored the overwhelming vote in Scotland to remain. They’ve dismissed all attempts at compromise from the Scottish Government.
“And they’ve disregarded – time and time again – the views of the Scottish Parliament. Taking Scotland out of the EU against our will does not deliver on the result of the referendum.
“For people in Scotland, pressing ahead with Brexit doesn’t deliver on the referendum – it overturns that referendum.”
And in a reference to her aim of holding a Scottish independence referendum by 2021, the First Minister will argue Scots should “keep our options open at this critical time. The future of our country is at stake.”