As the damaging Partygate scandal rumbles on, Boris Johnson is facing growing pressure to resign – both from within and outside of Tory ranks.
Despite tumbling approval ratings, and an increasingly fractious Conservative party, the prime minister has consistently brushed aside calls for his resignation – stating that he is focused on tackling the growing cost-of-living crisis and escalating tensions between Russia and Ukraine.
Meanwhile, the Metropolitan Police has begun investigating suspected rule-breaking in Number 10, and a separate inquiry into reported lockdown parties could be published in the coming days.
The report has the potential to bring down the prime minister, with a number of Tory MPs understood to be poised to submit letters of no confidence depending on its contents.
If Johnson is ousted, will there be a general election?
Why are we asking the question now?
On Tuesday night, Jacob Rees-Mogg told BBC’s Newsnight that a general election would have to be called if Boris Johnson was replaced as leader of the Conservative Party.
The Leader of the House of Commons argued that any new PM would need to go to polls in order to shore up support from the public.
He said: “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."
However, constitutionally speaking, this is not correct the public elects the party to lead, not just the prime minister.
Conservative leaders can be replaced without the need for a general election via the party's internal process.
This is what happened when Boris Johnson took over from Theresa May in summer 2019.
He only held the winter 2019 general election due to his desire to get a large enough majority to get a Brexit bill through parliament, not out of a constitutional requirement.
What would need to happen for a Conservative leadership contest?
For a Tory party leadership contest to be launched, one of two things would need to happen.
The first is that Johnson decides to resign, which would trigger a leadership election.
The second is Conservative MPs decide they want to sack the prime minister.
To do this, 54 letters of no-confidence from Johnson's own MPs would need to be sent into the party's 1922 Committee, which oversees the constitutional workings of the party.
It is unknown how many MPs have already submitted a letter, but less than 10 have publically declared they have -
Many more could act if the Sue Gray report's findings are damning.
Following that, a no-confidence vote would be tabled, which would require more than 50% of sitting Tory MPs to vote to oust him.
Should that happen, a party leadership contest would commence; this also happened to Theresa May, but she survived a no-confidence vote.
Tory MPs would then be invited to throw their hat into the ring to run for leader and, in this case, for prime minister - trying to galvanise support from their party colleagues and the party's membership base, with the process taking around six weeks.
Each person vying for leader needs to be nominated by at least two other Tory MPs.
Eventually, the contest is whittled down to two candidates via a ballot system by the MPs, then Conservative party members having the final say on which one gets the top job.
Some have criticised the system for being undemocratic given that Tory members decide on the prime minister, not the general public.
Would a new leader have to go to the polls?
The new prime minister would not need to go to the polls.
However, previous PMs who have taken office by becoming the leader of the governing party have faced criticism for not calling an election.
When Gordon Brown became prime minister after replacing Tony Blair in 2007 as leader of the Labour party, he led the country for three years without calling an election.
Brown was criticised for not having a mandate, with suggestions that the public was not behind him.
And, when he fought a general election in 2010, he lost.
What would need to happen for a general election?
When it comes to calling a general election, there are two methods.
The first is parliament voting for one.
During the coalition government, David Cameron introduced legislation called the Fixed-term Parliament Act 2011, which essentially blocked the government from independently calling a snap election when convenient, such as if they were ahead in the polls.
Under the Act, two-thirds of MPs must vote to trigger a general election, as was the case in 2019.
However, in 2019, both Labour and the Conservatives pledged in their manifestos to repeal the act.
The Conservatives argued it "led to paralysis at a time the country needed decisive action”, with Labour arguing it "has stifled democracy and propped up weak governments”.
The second key way a general election can be called is if MPs as a whole pass a no-confidence vote in the House of Commons.
If the motion is successful, and no alternative government is confirmed by the Commons within 14 days, a general election is called.
Watch: PM insists 'I am getting on with the job' as partygate report looms