Prime Minister Rishi Sunak faces a third by-election test after a close ally of Boris Johnson resigned from the Commons with "immediate effect".
In a tumultuous 24 hours for the Conservative Party, Nigel Adams MP announced on Saturday that he was following the former prime minister and former culture secretary Nadine Dorries' lead in quitting Westminster.
In a tweet, Mr Adams said: "Yesterday, Selby Conservatives selected an excellent new parliamentary candidate.
"I've today informed the chief whip that I will be standing down as a Member of Parliament with immediate effect.
"It has been an honour to represent the area where I was raised (and) educated."
It comes after former Cabinet minister and staunch Johnson loyalist Ms Dorries, who had previously detailed her plan to quit as the MP for Mid Bedfordshire at the next election, announced on Friday that she would be standing down "with immediate affect".
Ms Dorries, alongside Sir Alok Sharma - president of the Cop26 climate summit in Glasgow - had been tipped for peerages in the honours list.
But reports ahead of the publication suggested the Government cut her from the list at the 11th hour to swerve an early election battle in her seat.
The publication of the list, late on Friday, confirmed that neither Ms Dorries, nor Sir Alok were to be elevated to the Lords.
Ms Dorries, who has been a frequent critic of Mr Sunak since he took office last autumn, had earlier told TalkTV that "the last thing I would want to do would be to cause a by-election" in her seat.
But speaking to the broadcaster after the announcement, she admitted that "something significant did happen to change my mind".
"The bottom line is really, I'm doing my own show on TalkTV and I write a column in the Daily Mail every Tuesday, which takes a lot more time than I ever thought it would do," she told TalkTV.
"It's actually hard work.
"I've been working like seven days a week and I'm also managing these outside jobs as well as my role as an MP.
"And the House of Lords thing was on the cards and it's gone back to Holac (House of Lords Appointments Commission) for MPs to be vetted or whatever and I just thought, you know, I think this is the time actually for me to stand down."
She also appeared to issue a coded warning to Mr Sunak, whom many allies of the former prime minister blame for his downfall.
She said: "A prime minister doesn't have the ability to change the list of a former prime minister. The list that Boris had was agreed with Rishi and that was done.
"Can you imagine if Rishi suddenly decided 'I am going to remove somebody from Boris' list?'
"He would be setting a precedent that has never been set before.
"A prime minister doesn't do that. They'd be a very foolish prime minister who tampered with the list of a former prime minister because he'd end up not getting his own nominations through."
The prospects of such an electoral test would have been challenging for the Prime Minister in Sir Alok's marginal Reading West constituency, where he has a 4,000-vote majority over Labour.
It remains unclear whether Ms Dorries or some of her fellow Johnson-era Cabinet ministers will now get the expected peerages. A No 10 source indicated that there is no precedent for a prime minister's resignation list to be re-issued.
But Ms Dorries' immediate resignation will nonetheless cause a headache for the Prime Minister, forcing him to fight a by-election.
The senior Tory MP won 60% of the vote in the Mid Bedfordshire constituency at the 2019 general election, well ahead of Labour in second place on 22% and currently has a 24,664 vote majority from 2019.
Former Conservative Party leader Lord Hague said it was "a big thing to cause a by-election unnecessarily".
"I can't say I approve of causing a by-election unnecessarily," he told Times Radio.
"It's a shame that she's done it in that way."
Ms Dorries had been an MP since 2005, and is set to release a book on Mr Johnson's exit from office.
Her promotion to culture secretary under Mr Johnson saw her lead the now-ditched plan to privatise Channel 4.
She was no stranger to controversy during her time in Parliament, losing the Conservative whip in 2013 as a result of her appearance on ITV's I'm A Celebrity... Get Me Out Of Here!
Scotland Secretary Alister Jack and former Cabinet Office minister Mr Adams had also initially been named among those expected to get peerages.
Today, veteran Conservative MP and arch Eurosceptic Sir Bill Cash and health minister Will Quince also announced they will step down at the next election.
