More Tory MPs have tabled a letter of no confidence in Boris Johnson, as calls for his resignation as prime minister continue.
Conservatives Andrew Bridgen and Elliot Colburn confirmed on Monday that they had delivered letters of censure, joining a growing number of colleagues.
It comes as reports of potentially more breaches of the coronavirus rules at No 10 emerge beyond the conclusion of the Metropolitan Police investigation and the report by civil servant Sue Gray.
For a prime minister to be elected, the incumbent must resign, his party must lose the next general election, or he must lose a vote of no confidence.
With different parties having different rules, here we look at how a conservative prime minister can be ousted.
– What are the conservative rules for a vote of no confidence?
Mr Johnson has shown no signs of being ready to step down and a next general election is scheduled for 2024, meaning those options appear to be off the table.
But a Conservative Party leadership race could be triggered if Mr Johnson were to lose a vote of confidence among his own MPs.
A total of 54 letters of no confidence from Tory MPs, 15% of the parliamentary party, would have to be submitted to Sir Graham Brady, chairman of the 1922 Committee of Backbenchers, for a vote to take place.
Letters from MPs are kept on file by Sir Graham, unless withdrawn, and he keeps a secret count of the number.
If the 15% threshold is reached, he will announce a vote of no confidence.
At least 50% of Tory MPs must vote ‘no confidence’ for the Prime Minister to lose.
A leadership race would then begin, with Mr Johnson unable to stand as a candidate.
If he survives, he would get a 12-month reprieve from future censorship bids from the parties.
More than 20 MPs have publicly declared they want a vote, although it is unclear whether all have written to Sir Graham.
Meanwhile, others may have sent a letter without declaring it, making exact numbers difficult to know.
– How does a Conservative leadership race work?
The competition takes place in two stages.
In the first stage, Conservative MPs present themselves as candidates.
All Tory MPs then vote in a series of rounds to reduce the number of candidates until only two remain.
The second stage of the competition sees the two remaining candidates put to a vote by members of the Conservative Party.
Boris Johnson won the 2019 leadership race against Jeremy Hunt, following the resignation of Theresa May.
– What is a motion of confidence?
A motion of confidence is a way to check whether the Prime Minister and his government still have the support of the House of Commons.
Opposition parties can introduce such a motion and if it receives enough support, it can be chosen to be debated in the House before being put to a vote.
Under rules in place since 2011, if the government loses the vote, it has 14 days to try to win back the confidence of MPs with another vote.
At the same time, opposition parties can try to form their own alternative government.
After a fortnight, if no resolution is found, an election is automatically triggered.
During the Brexit stalemate, Theresa May survived a vote of confidence in January 2019 after it was requested by then Labor and opposition leader Jeremy Corbyn.
The Liberal Democrats tabled a no-confidence motion against Boris Johnson’s government in January, shortly after the party’s allegations first surfaced, but it failed to win enough support.
Even if a ballot is held, MPs tend to vote along party lines when it comes to a vote that could bring down the government.
Given that Mr Johnson has a working majority of 77, even a notable number of MPs who rebel against that norm over the party deal are unlikely to see him overthrown.
– Will the Prime Minister survive?
Mr Johnson has made a career out of sailing close to the wind and has refused to quit despite several waves of MPs calling on him to do so.
Mr Bridgen, who resubmitted his letter of censure after the original was withdrawn in March due to the invasion of Ukraine, suggested on Monday that the tally could now be ‘close’ to triggering a ballot .
Yet even if a ballot is called, 179 of the current 357 Tory MPs would have to vote “no confidence” to trigger a leadership election.
If Mr Johnson avoids or survives a vote of no confidence, his authority has always been badly damaged and leaves him vulnerable to further crises, such as rising costs of living.