Prime Minister Liz Truss has "12 hours" to save her job after her government descended into fresh chaos, a senior Conservative MP has warned.
Simon Hoare said: "I think today and tomorrow are crunch days."
Cabinet ministers are rallying around Ms Truss but a growing number of her MPs believe her time is up.
Her attempts to reassert her authority were torpedoed by the resignation of the home secretary and farcical scenes after a Commons vote on Wednesday.
All eyes will be on Sir Graham Brady, chairman of the powerful backbench 1922 committee, who could tell Ms Truss she no longer has the support of her MPs, if enough of them sign letters calling for her to go.
Mr Hoare said there was "a growing sense of pessimism in all wings of the Tory party."
"Usually it's one or the other, but to have it across the party should be ringing alarm bells," he added.
There is also speculation that senior figures in the party could agree on a replacement for Ms Truss, which would avoid the need for another Tory leadership contest, or a general election.
So far 10 Conservative MPs have publicly called for the prime minister to resign.
But the different factions in the party are split over who should take on the job.
Transport Secretary Anne-Marie Trevelyan said the cabinet still has confidence in Ms Truss.
But under questioning on the Today programme, Ms Trevelyan declined to say whether Liz Truss will lead the Conservatives into the next election.
"I want her to continue delivering the really important work we're doing," she said.
Ms Truss appears determined to fight on - and is attempting to reassert her authority after another day of turmoil, which began with her firing Home Secretary Suella Braverman.
She appointed Grant Shapps, one of her harshest internal critics, who she had sacked six weeks earlier as transport secretary, as Ms Braverman's replacement.
A Labour attempt to get a new law through banning fracking sparked havoc in the Tory ranks.
MPs were threatened with the expulsion from the party if they did not back the government, despite many of them being vehemently opposed to fracking.
Just before they were about to vote, climate minister Graham Stuart told them it would not be treated as a confidence vote in Ms Truss, which some took to mean they could back the Labour motion without fear of being sacked.
This led to chaotic scenes as MPs who wanted to vote in favour of a ban on fracking were confronted by cabinet ministers ordering to them to vote with the government.
For several hours, it was not clear whether the government chief whip Wendy Morton - the woman in charge ensuring MPs vote the way they are told - had resigned or not.
Overnight, the government issued a statement saying Ms Morton remains in her job - and the fracking vote had always been a confidence vote in the PM.
The Tory MPs who voted in favour of Labour's fracking ban motion would face "proportionate disciplinary action", the government said.
After the chaotic scenes on Wednesday night, Conservative MP Sir Charles Walker said he was "furious" with the "shambles" - and there was "no coming back" for the government.
Later he added: "I expect the prime minister to resign very soon because she's not up to her job."
Some Conservative MPs said Sir Charles was speaking for all of them.
On Thursday, asked if the government was fully functioning, Kemi Badenoch said: "It's quite clear that there's quite a lot of turmoil in the party.
The International Trade Secretary added: "What we all need to do is keep calm heads and work to resolve it and I'm confident that we can do that."
Conservative MP Crispin Blunt said Ms Truss's position is "wholly untenable".
"If she doesn't understand that then I would be astonished," he said.
The Conservative MP for Waveney, Peter Aldous said the "window of opportunity" for Ms Truss to win his confidence is "very rapidly diminishing, if it hasn't closed altogether".
Mr Aldous said in the voting lobbies last night there was "exacerbation and anger" at the government.
If the PM does resign, Mr Aldous said he sees Rishi Sunak or Penny Mourdant as the likely successors.
Source: BBC
Image source: simonhoare.org.uk
