Rishi Sunak is facing a third by-election after a close ally of Boris Johnson said he is stepping down from the Commons with “immediate effect”.
Conservative MP Nigel Adams has announced he is following the former prime minister and former culture secretary Nadine Dorries out the door of Westminster.
The MP for Selby and Ainsty previously said he would quit at the next general election.
Politics latest: Nigel Adams latest MP to quit after Johnson and Dorries
But in a tweet on Saturday, he said the Selby Conservatives had selected an “excellent new parliamentary candidate” and he has today “informed the chief whip that I will be standing down as a Member of Parliament with immediate effect”.
He added: “It has been an honour to represent the area where I was raised, educated.
“I want to thank my constituents for their wonderful support since 2010.”
The move has led to renewed calls from opposition MPs for the prime minister to call an early general election.
Mr Adams is a long-standing ally Mr Johnson’s, having supported him to be Conservative leader in 2016 when he decided not to throw his hat in the ring.
Both he and Ms Dorries had been tipped for peerages in Mr Johnson’s resignation honours but neither featured in Friday’s published list.
There has been speculation that Downing Street wanted their names removed to avoid potentially damaging by-elections, although Number 10 said Mr Sunak had no involvement in producing the final list.
While the Tories enjoy a comfortable majority in both their constituencies, the decision to exit immediately rather than wait until the next election means the Conservatives will face contests on three fronts at a time when they are flailing behind Labour in the national polls.
Mr Johnson sensationally quit on Friday after receiving a report into the Commons investigation about whether he lied to MPs over partygate.
While the privileges committee’s findings have yet to be released, Mr Johnson’s response appears to confirm that the MPs have concluded he had not been truthful about the boozy parties and recommended a 10-day suspension from the Commons as punishment – something which could have triggered a by-election in his marginal west London seat.
In a scathing 1,000-word resignation statement, Mr Johnson said he was being “forced out” of parliament by a probe that he claimed had set out from the beginning to “find me guilty, regardless of the facts”.
He said the seven-person panel, which is chaired by veteran Labour MP Harriet Harman but has a Conservative majority, was on a “witch hunt” and compared it with a “kangaroo court”.
But critics of Mr Johnson branded him a “coward” and said he “jumped before he was pushed”.
The former Tory leader’s Uxbridge and South Ruislip seat was in Labour’s top 100 targets at the next election even before Mr Johnson’s resignation, and polling suggests the Opposition has a 14-point lead over the Tories there.
Labour has already launched its campaign to win the seat, saying in an email to members that victory is a “vital next step” if they wish to form a government.
Meanwhile, the Liberal Democrats have briefed that they could potentially pull off an upset in Ms Dorries’ former Mid Bedfordshire constituency.
The former cabinet minister resigned hours before Mr Johnson on Friday, telling her TalkTV channel “something significant did happen that changed my mind” – though she refused to say what that was.
Rishi Sunak is yet to comment on the tumultuous events of the past 24 hours.
News of Mr Adams’ resignation prompted Labour’s shadow business secretary Johnathan Reynolds to tweet: “By election by stealth?”
This was echoed by Liberal Democrat deputy leader Daisy Cooper, who said: “The Conservative Party is in meltdown and must now call a general election.
“After years of failing our NHS and failing to deal with the cost-of-living crisis it is time people across the country have their opportunity to give a verdict on this chaotic Conservative Government.”