After months of anonymous threats and speculation, Boris Johnson will face a confidence vote by Tory MPs this evening. Announcing the news this morning, the chair of the 1922 committee Sir Graham Brady said in a statement:

‘The threshold of the 15% of the parliamentary party seeking a vote of confidence in the leader of the Conservative Party has been exceeded.

In accordance with the rules, a ballot will be held between 18:00 and 20:00 today MONDAY 6th JUNE – details to be confirmed.’

So, what comes next? No. 10 have chosen to move quickly – as Theresa May did when she faced a confidence vote and won it. It will be held this evening with the votes to be counted immediately afterwards. A Downing Street spokesperson has described the vote as ‘a chance to end months of speculation and allow the government to draw a line and move on, delivering on the people’s priorities’. They added that Johnson ‘welcomes the opportunity to make his case to MPs and will remind them that when they’re united and focused on the issues that matter to voters there is no more formidable political force’.

This vote has not come as a surprise to supporters of the Prime Minister. In the past week, there has been a consistent turn in the mood against Johnson within the Tory party – following the publication of the Sue Gray report into partygate. MPs from across the party have come out to voice their discontent. Speaking to Andrew Neil on Channel 4 on Sunday evening, business minister Paul Scully admitted that a confidence vote was likely – insisting the Prime Minister would face down his critics and win it. However, the trouble with confidence votes is that even if a leader technically wins one, they tend to weaken rather than strengthen them – May won hers but she still left her No. 10 within six months – and momentum is building against Johnson.

Former minister Jesse Norman is the latest senior conservative to come out against him – issuing a statement this morning criticising the direction of this government. Johnson and his team will use the coming hours to try to shore up his position. The belief in No. 10 is that he ought to win this comfortably – it’s why some of the rebels hoping to oust the Prime Minister would have preferred to wait until after this month’s two by-elections. But despite this, the vote presents a moment of peril for Johnson. While Johnson allies say he will fight on if he wins it no matter what the margin is, benchmarks are already being discussed as to what counts as a victory. Tonight’s vote risks exposing dwindling support for his leadership amongst a majority of backbenchers.