By Westminster Producer Lewis Denison
Boris Johnson is so far holding onto the role of prime minister - but many in Westminster don't believe his premiership can last beyond the local elections in May.
Allegations of Covid-rule-breaking are piling up against the PM, with an internal investigation looking into at least nine potentially lockdown-breaking parties which took place during the pandemic.
The outlook for Mr Johnson was not good after he apologised for attending one of those bashes himself (claiming he thought it was a work event) but the revelation that his staff partied in Number 10 the day before Prince Philip's funeral has been described as the "nail in the coffin" by a source in government.
Several letters of no confidence in the PM have already been submitted by Tory MPs hoping to remove him as party leader, but the number is well short of the 54 required to trigger a vote on his leadership - click here to learn exactly how the process works.
Winning the May elections - if he can hold on til then - could be his final chance at redemption, but a loss would surely spell the end of Prime Minister Boris Johnson.
Here's a list of the Tories our political journalists think might run to replace him:
Rishi Sunak, chancellor of the Exchequer
Rishi Sunak was tipped as a rising star in the Conservative party even before he became chancellor, but that appointment saw him swiftly become the bookies favourite to replace Boris Johnson.
The odds have tightened dramatically since then but Mr Sunak is still among those at the front of the pack.
At 41-years-old, Mr Sunak is the youngest potential candidate identified by the ITV News Politics team and his slick social media operation means he's able to reach a younger demographic than many of the others.
The ambitious MP has previously been criticised by other Tories for his "brand Rishi" approach to social media, which has seen him employ tactics such as incorporating his own name into the Conservative Party logo.
Some have suggested this is a strategy to align himself with the party and become the natural replacement for Mr Johnson.
Mr Sunak has been absent throughout much of the partygate scandal, a move characterised by many as a bid to distance himself from the scandal.
Despite still enjoying popularity, the cost-of-living crisis could change all that, with households set to face a double blow in April of rising energy bills and National Insurance contributions.
Liz Truss, foreign secretary
Liz Truss was something of an unknown entity to those outside the Tory party before she took over from Dominic Raab as foreign secretary.
But she was a favourite among party members well before her appointment and has only grown in popularity since then.
The foreign secretary is currently the party membership's favourite to replace Mr Johnson - according to Tory website Conservative Home which surveyed its readers - leading Mr Sunak by 3% of the votes.
Her patriotism, well-known due to a now infamous speech about cheese, and tough stance on Brexit make her popular among the members.
At 46, she is five years older than her closest rival and has been an MP for five years longer than he has.
Sajid Javid, health secretary
Despite entering Parliament at the same time as Ms Truss, Sajid Javid is vastly more experienced as a top politician.
The 52-year-old - who ran against the current PM in the 2019 leadership election to replace Theresa May - has held numerous senior roles in government, including previous stints as chancellor, business secretary and culture secretary.
He is no where near as popular as the two front runners among readers of Conservative Home, but his performance so far as health secretary has seen him win fans in the general public.
His background as the son of immigrants, whose father was a bus driver, could make him more appealing to Tory members looking ahead to a general election where working-class appeal will be important.
But he finished in fourth place when running against Mr Johnson in 2019 and campaigned for the UK to remain in the EU in 2016, meaning he might struggle in any forthcoming leadership contest.
Michael Gove, secretary for levelling up
Michael Gove, 54, has been an MP for more than 16 years and only spent one year outside of the Cabinet since 2010.
He's been considered a potential leader much longer than anyone else in contention and his experience means he'll be one of the favourites if he decides to run for the leadership again
It would be his third attempt, after failing to beat both Theresa May in 2016 and Boris Johnson in 2019.
But he is very highly regarded within the parliamentary party and despite long being considered a rival to Mr Johnson, he has always been a senior member of Cabinet.
The levelling up secretary - who recently got divorced - finished third place when running against the current prime minister, failing to win enough nominations from Tory MPs to make the final ballot.
According to Conservative Home, Mr Gove is the eighth most popular Cabinet minister among Tory voters.
Dominic Raab, deputy prime minister
Former lawyer Dominic Raab has held top roles in government, such as foreign secretary and justice secretary, and is also the deputy prime minister.
He's acted as Mr Johnson's right hand man for much of the PM's time in office - he even stood in as acting prime minister when the incumbent was in hospital with coronavirus.
But he was heavily criticised for remaining on holiday during the Taliban's recapture of Afghanistan and was punished for what has been described as a disastrous response to the crisis with a demotion.
He remained in government however and managed to hold onto his role as deputy prime minister, meaning he would be considered a continuity candidate among those who support Mr Johnson's policies.
But he struggled to win support from Tory MPs after announcing his intention to replace Theresa May in 2016 and finished sixth in the race.
Priti Patel, home secretary
Priti Patel is a divisive figure in UK politics; generally speaking she is liked by the right and loathed by the left.
The 49-year-old is tough on crime and immigration as home secretary, something that sits well with a majority of Tory members. She was also a prominent figure in the Vote Leave campaign for Brexit during the 2016.
She was found to have broken the ministerial code in 2020 after an investigation agreed with accusations that she'd bullied staff, but the PM showed her loyalty by keeping her in his Cabinet.
The home secretary has been an MP since 2010 and held other senior roles such as international development secretary before being sacked by Theresa May for holding unofficial meetings with Israelis.
Her popularity among Tory members has fallen during the pandemic; she ranked fourth favourite in March 2020 but is now outside the top ten, according to Conservative Home.
Jeremy Hunt, chair of Health and Social Care Committee
Jeremy Hunt is by far the most experienced backbencher on this and perhaps the most experienced of all, apart from Michael Gove.
He's held numerous senior roles in government since becoming and MP in 2005 and was most recently foreign secretary before being booted out of Cabinet by Boris Johnson when he took over from Theresa May.
He was previously the UK's longest standing health secretary - where he gained enemies in the NHS over battle to change junior doctor contracts - and before that was culture secretary.
The 55-year-old has often been critical of the government's handling of the coronavirus pandemic, something which appears to have gained him fans.
He finished second in the 2019 leadership contest after seeing off competition from nine other candidates before being defeated by Boris Johnson. He lost with 33.6% of the vote.
The MP signalled he might run again in an interview with The House Magazine, saying he still has ambitions to lead the Tory party.
He said: "I wasn't expecting to leave the government in 2019, but I've enjoyed being on the backbenches much more than I thought.
"I won't say my ambition has completely vanished, but it would take a lot to persuade me to put my hat into the ring."
Penny Mordaunt, currently trade minister who has held numerous senior roles
The most senior role Penny Mordaunt held in government was defence secretary, a position she held for just three months before being sacked by Boris Johnson when he become PM.
She was eventually brought back into government and is now a trade minister after moving on from being paymaster general.
The 48-year-old also served in David Cameron's government as a Parliamentary under-secretary and as international development secretary under Mrs May.
Ms Mordaunt, who has been an MP since 2010, was described by Politics Home as a the "dark horse" of any leadership election.
The politics website says it understands several Tory MPs have already privately voiced support for her, if she were to throw her hat into the ring.
And her other job as a member of the Royal Navy Reserves means she's likely to be popular among Tory voters.
Mark Harper, former chief whip and rebel leader
Despite being on the backbenches consistently since 2016, Mark Harper is an experienced parliamentarian and is a former chief whip in the Tory party.
He joined Parliament in 2005 and held other senior roles in government such as Home Office minister and work and pensions minister.
The 51 year old is seen to be well liked by grassroots Conservatives, both for his support of Brexit and opposition to coronavirus restrictions.
He also ran to replace Theresa May but was eliminated in the first round ballot because he failed to secure enough support from Tory colleagues.