Boris Johnson’s leadership hangs in the balance as he waits for the release of Sue Gray’s report into alleged rule-breaking parties in Downing Street.
A number of the prime minister’s own MPs have already called on him to resign amid the allegations, but the PM has so far refused to step down.
For a Conservative party leadership contest to be triggered, a significant number of Tory MPs would have to turn against Mr Johnson.
What is a vote of no confidence and what would happen after it?
MPs who want a leadership election mean that they have ‘no confidence’ in their current leader by writing a letter to Sir Graham Brady, chairman of the backbench 1922 Committee.
If Sir Graham receives 54 letters – from 15 per cent of Tory MPs – a vote on Mr Johnson’s leadership would be held.
This is referred to as a ‘vote of no confidence’.
If more than 50 per cent of all Tory MPs vote in support of the PM, he will remain as prime minister and cannot face another vote for 12 months.
However, if Mr Johnson loses the vote, he would be out and Tory MPs and members would vote for a new leader.
Any leader who loses a confidence vote is not allowed to take part in the subsequent leadership contest.
It is understood that many of Mr Johnson’s critics have held off from putting in formal letters of no confidence as they await the findings of Ms Gray’s report.
Scottish Conservative leader Douglas Ross recently said that rebel Tory MPs are getting “closer and closer” to the 54 letters needed.
He said the situation was a “rollercoaster ride” as some MPs were withdrawing their letters in response to party whips.
Mr Ross spoke to the BBC a week after he called on Mr Johnson to resign.
I have suggested there are “far more” than just the Tory MPs who have publicly stated their anger.
However, he admitted that only committee chairman Sir Graham knew the exact number.
If a Tory leadership contest is triggered, it will take place in two stages.
In the first stage, Conservative MPs put themselves forward as candidates.
All Conservative MPs then vote in a series of rounds to reduce the number of candidates until only two remain.
The second stage of the contest sees the two remaining candidates put to a vote of Conservative Party members.
At the moment, the current favorites to stand in a leadership election include chancellor Rishi Sunak and foreign secretary Liz Truss.
Will a general election be held?
A vote of no confidence from Tory MPs would not trigger a general election – only a Tory leadership contest.
If that happens, there is no rule saying that the new Tory leader would have to call a general election.
The next general election is scheduled to take place on May 2 in 2024.
There are two ways that a general election could take place earlier than this.
Firstly, if the House passes a motion of no confidence in the government. The government would have 14 days to bring forward a replacement government and get its approval. If this doesn’t happen, an election would be triggered.
Secondly, a general election could be triggered straight away if two-thirds of the total number of MPs sitting vote in favor of one.
Earlier today, Commons Leader Jacob Rees-Mogg suggested there would have to be a general election if Mr Johnson is ousted.
He told BBC’s Newsnight: “It is my view that we have moved, for better or worse, to essentially a presidential system and that therefore the mandate is personal rather than entirely party, and that any prime minister would be very well advised to seek a fresh mandate.”