Boris Johnson is facing further calls to resign, with Tobias Ellwood joining those Tory MPs urging a vote on his premiership.
The former minister said he had submitted a letter of no confidence in the PM, amid the ongoing row over lockdown parties in Downing Street.
Devon MP Anthony Mangnall also revealed on Wednesday he has done the same, criticising Mr Johnson’s “mistruths”.
At PMQs, Mr Johnson did not address questions about events held in No 10.
A handful of Tory MPs have publicly revealed they have submitted letters to the backbench group which runs leadership contests.
At least 54 need to write to the committee chairman Sir Graham Brady to set up a vote on the PM’s future.
But the exact number of MPs who have taken this step is not known.
Mr Johnson is seeking to head off a leadership challenge prompted by weeks of damaging headlines about parties in government buildings held whilst Covid restrictions were in place.
At Prime Minister’s Questions, Mr Johnson refused to confirm press reports that he was at a party in his Downing Street flat on 13 November 2020.
The gathering is one of 12 events in Downing Street and Whitehall being investigated by the Metropolitan Police for alleged Covid-rule breaking.
The SNP’s Westminster leader Ian Blackford claimed Mr Johnson misled MPs in December last year when he denied being at this event.
“Surely he doesn’t need to wait for an investigation to tell us exactly where he was?” asked Mr Blackford.
Mr Johnson said processes had to be followed and he was getting on with delivering the government’s recovery plan.
Mr Ellwood, who chairs the Commons Defence Committee, called on the PM to “cut to the chase, to call a vote of confidence in himself” and said the party was on a “glide path to a very, very dark place”.
He told BBC News the prime minister had not shown enough “contrition” in his Commons statement on Sue Gray’s report, on Monday, and had already had plenty of time to make the changes he had promised.
He praised Mr Johnson’s “energy and enthusiasm” but added: “The domestic and international challenges now require a new leader and that’s why I have submitted a letter.”
Anthony Mangnall, Tory MP for Totnes and South Devon, also revealed shortly after PMQs he had submitted a no-confidence letter in the PM.
He tweeted: “At this time I can no longer support the PM. His actions and mistruths are overshadowing the extraordinary work of so many excellent ministers.”
Another former minister told the BBC on Wednesday they had resolved to submit a no-confidence letter in the PM, but they are waiting until they are sure he would lose the subsequent vote.
Under Tory party leadership rules, Mr Johnson would be safe from another challenge for a year if he won a no-confidence vote in his leadership.
The former minister added that colleagues “didn’t want to jump the gun” and then be “powerless to act for another year”.
“The end is almost inevitable. The question is – is now the right time to put a letter in?” they added.
Meanwhile, Downing Street has refused to comment on reports of Mr Johnson’s further attendance at some of the events being investigated by police.
The Daily Telegraph reported he attended an event for two departing officials on 14 January 2021 – with the Guardian adding that he gave a speech and stayed for “around five minutes”.
The Telegraph also said he attended an event for another departing official on 17 December 2020, and a gathering in his Downing Street flat on 13 November 2020.
Asked about the reports, No 10 said it would not comment on the Met’s ongoing investigation.
Writing on his blog on Tuesday, the PM’s former aide Dominic Cummings claimed he had spoken to people who were in No 10 on that date and “could hear the party” in the flat.
“I’ve spoken to people who say they’ve seen photos of parties in the flat,” he added.
Savile remarks row
Mr Johnson is also facing calls to withdraw a claim he made in the Sue Gray debate on Monday that Sir Keir Starmer failed to prosecute Jimmy Savile when he was director of public prosecutions (DPP).
Tobias Ellwood and other Conservatives have criticised the PM for these comments, with Mr Ellwood suggesting it was one of the reasons he decided to submit a letter of no confidence in him.
Sir Keir has called Mr Johnson’s comments a “ridiculous slur” – and he made a brief statement on them at Prime Minister’s Questions.
Addressing Conservative MPs, the Labour leader said: “Theirs is the party of Winston Churchill. Our parties stood together as we defeated fascism in Europe.
“Now their leader stands in the House of Commons parroting the conspiracy theories of violent fascists to try and score cheap political points. He knows exactly what he was doing. It’s time to restore some dignity.”
The Labour leader was head of the Crown Prosecution Service in 2009 when Surrey Police interviewed Savile and consulted a CPS lawyer, who decided there was insufficient evidence for a prosecution to take place.
The CPS has said Sir Keir was not the reviewing lawyer on the case, and there is no mention of his involvement in a 2013 review into the case.
Nazir Afzal, a former chief crown prosecutor for the North West, said on Monday: “It’s not true. I was there. Keir Starmer had nothing to do with the decisions taken.”
On Wednesday, senior Tory Sir Bob Neill called on Mr Johnson to withdraw his claim – calling it “baseless and unworthy”.
He joins former Northern Ireland secretary Julian Smith, who said on Tuesday the PM’s accusation was “wrong and cannot be defended”.
