She did not set a new date for the vote. One trenchant critic, the North East Derbyshire MP, Lee Rowley, told her: "Stamina is not a strategy".
He was confident voters would choose to remain, but on June 23, 2016, they voted by 52 per cent to 48 per cent to leave.
In a bid to win over wavering lawmakers, May indicated she would step down before the next election, due in 2022.
May could face a further no-confidence motion from opposition parties if she survives Wednesday's vote.
Already, cabinet ministers are speculating about which way she can tack. But her authority was seriously undermined by the botched early general election she called a year ago which, instead of consolidating the Conservatives' hold on power, ended up with Mrs May losing her overall parliamentary majority.
Another Tory legislator, Nick Boles, tweeted: "She was unambiguous". "But the word "intention" is a classic politician's word, because intentions can change".
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The threat to May has been building as pro-Brexit Conservative lawmakers grew increasingly frustrated with the prime minister's handling of Brexit.
But facing a huge rebellion of her own Tory MPs, primarily over the backstop clause created to keep open Britain's border with Ireland, May conceded she expected to lose and delayed it.
However a significant mutiny could make her leadership untenable. A secret ballot is being held between 1800 and 2000 GMT.
As leader of the largest party in the Commons, the new Conservative leader would then be expected to be asked to form a government and become prime minister, without a general election. Foster later said: "We emphasised that tinkering around the edges would not work".
Not much. Britain is seeking "reassurances" that the backstop will be temporary. "We wanted fundamental legal text changes".
Briefing EU lawmakers in Strasbourg, France, on this week's leader's summit, Juncker said Tuesday that "there is no room whatsoever for renegotiation" of the divorce deal.
"I will now do everything I possibly can to secure further assurances", May told mutinous MPs Monday on her planned dash to Europe ahead of an European Union summit later this week. "People referenced her stamina, frankly".
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Asked by NBC why kids liked watching his videos , Ryan - who is now 8 - replied: "Because I'm entertaining and I'm amusing ". Daniel Middleton , the Minecraft gamer who topped the 2017 list with earnings of $16.5m, has slipped to fourth place.
Leadsom said she backed May in the confidence vote.
Speaking to reporters outside 10 Downing Street, May vowed to "contest that vote with everything I've got". "She must now bring her dismal deal back to the House of Commons next week so Parliament can take back control".
The Labour leader accused her angrily of treating parliament in a "totally and utterly unacceptable" way; and pressed her to say when she will stage the delayed "meaningful vote" on her Brexit deal.
Mrs May's predecessor as Conservative PM, Sir John Major, called for an immediate halt to the two-year Article 50 process leading to United Kingdom withdrawal from the European Union on March 29, declaring: "The clock must be stopped". "We were promised strong and stable".
"The deal that we have achieved is the best deal possible, it is the only deal possible", he reiterated.
But a rising number of backbench lawmakers, along with three of the four living former prime ministers, say the only way out of the impasse may be a new referendum with an option to stay. But the prime minister has said that she'll go - though not just yet. "Every leader's made the mistake of feeding this monster, that always then turns around and gobbles them up", she said.
Former Foreign Secretary Boris Johnson and former Brexit Secretary Dominic Raab are the bookmakers' favourites for the top job if May loses the confidence vote.
May's Brexit deal vote will go ahead, despite opposition
After months of negotiations, the Brexit deal has been thrashed out. That's something May has said won't happen on her watch.