Former minister Jesse Norman has submitted a no-confidence letter in Boris Johnson, calling his response to the Partygate report “grotesque”.
In a letter to the prime minister posted on social media, the MP for Hereford and South Herefordshire said Mr Johnson had presided over “a culture of casual law-breaking” in Number 10.
Mr Norman said the prime minister’s current policy priorities were “deeply questionable” and that there were no circumstances in which he could serve in a government led by him.
He warned any breach of the Northern Irish Protocol would be “economically very damaging, politically foolhardy and almost certainly illegal”.
“You are the leader of the Conservative and Unionist party, yet you are putting the Union itself gravely at risk,” he wrote.
The MP also said the government’s Rwanda policy was “ugly, likely to be counterproductive and of doubtful legality” and that plans to privatise Channel 4 were “unnecessary and provocative”.
His comments on Monday morning came shortly before Sir Graham Brady, chairman of the backbench 1922 Committee, announced enough Tory MPs had requested a vote of confidence in Mr Johnson to trigger a contest.
In an email to Tory MPs, Sir Graham said the vote would be held between 6pm and 8pm on Monday.
To survive the vote - triggered amid intense anger over the Partygate scandal - the prime minister will need to win the support of 50 per cent of his colleagues in a secret ballot.
Earlier, health secretary Sajid Javid told BBC Breakfast a no-confidence vote was likely but “not what the country needs” just moments earlier.
“I hope there isn’t [a no-confidence vote] – you have to be prepared but I think that what the country wants is for the government to get on and focus on the job at hand, which we are,” he said.
Mr Javid said his colleagues were “entitled to their views” but that his view was the country did not need a leadership election.
“What we need is to all rally around the prime minister and focus on delivery and deliver for the British people,” he added.
Downing Street said Mr Johnson “welcomes the opportunity to make his case to MPs”, with a No 10 spokeswoman saying Monday evening’s vote was “a chance to end months of speculation and allow the Government to draw a line and move on”.
Additional reporting by Press Association
