There's no clear heir to Boris Johnston if the Prime Minister loses the historic vote of no confidence at 6pm tonight.
Health Committee chairman Jeremy Hunt, Foreign Secretary Liz Truss, Chancellor Rishi Sunak and chairman of the Foreign Affairs Committee Tom Tugendhat are among those topping the next Tory leader odds, but there's no obvious forerunner. if Mr Johnson resigns after tonight's vote, called by chariman of the 1922 Committee Sir Graham Brady.
If he loses, he must resign and the Conservative Party will hold a leadership election - a crushing blow just 906 days after he won the Tories' biggest majority since the 1980s.
A leadership election would take a few months. It starts with Tory MPs whittling the candidates down to two, followed by hustings to Tories around the country and a vote by the party membership.
Last time in 2019, there were 10 candidates for the Tory leadership - Boris Johnson, Jeremy Hunt, Michael Gove, Sajid Javid, Matt Hancock, Mark Harper, Andrea Leadsom, Esther McVey, Dominic Raab and Rory Stewart. But last time, Boris Johnson was the obvious frontrunner. This time, Tory MPs are divided and there is no clear heir to the crown.
Mr Hunt - who was the run-off candidate in 2019 - dealt Mr Johnson a major blow this morning by calling for him to go, saying: "We are not offering the integrity, competence and vision necessary to unleash the enormous potential of our country".
It's widely expected the Prime Minister will win the vote tonight. If 180 or more MPs back the Prime Minister, he is technically safe from a vote for another year. It doesn't mean he's out of the woods, though. The 1922 Committee is free to change the rules to force another vote in six months - something MPs have discussed before.
More importantly, even without a rule change, having 100 or more of his MPs vote against him would start a clock ticking against the Prime Minister.
Here we take a look at the candidates thought likely to throw their hats into the ring if there is a leadership election, and the odds being offered on each individual by betting company Betfred at 10.30 this morning:
Jeremy Hunt - 4/1
Frontrunner Mr Hunt, 55, was the last candidate standing against Boris Johnson in 2019.
He said this morning: "I will be voting for change" because otherwise the Tories are set to lose the next general election. We are not giving the British people the leadership they deserve. We are not offering the integrity, competence and vision necessary."
An MP since 2005, he was educated at £41,000-a-year public school Charterhouse and is a millionaire after founding the educational firm Hotcourses in 1990.
As Britain's longest-serving Health Secretary from 2012-2018, he sparked fury on the left for pushing through junior doctor contracts that were deemed dangerous. But in Tory eyes he is near the moderate, internationalist centre of the party, serving in a string of top roles, backing Remain and now chairing the Health Committee.
He and his Chinese-born wife, who he mistakenly said was Japanese in a bizarre 2018 gaffe while Foreign Secretary, have spent millions on a portfolio of luxury flats. He broke ethics rules by failing to declare his stake for six months.
Johnson loyalist Nadine Dorries launched an extraordinary Twitter tirade against Mr Hunt, declaring: "Your handling of the pandemic would have been a disaster." She added: "You’ve been wrong about almost everything, you are wrong again now."
Liz Truss - 7/1
Britain's first female Foreign Secretary has never confirmed she is running for leadership but it's a running joke in Westminster.
The 46-year-old comprehensive-schooled MP was born into a lefty family, chanting 'Maggie Maggie Maggie, out out out' with her mother and later protesting Tory policy as a Lib Dem activist.
She became an MP in 2010 after working as deputy director of the Reform think tank and has since become a darling of some sections of the Tory right, boasting the benefits of Brexit while International Trade Secretary and failing to defend judges who were branded "enemies of the people" when she was Justice Secretary. She has had to defend Tory tax rises but spoke out against a windfall tax on oil giants and insists she is a low-tax Tory.
Tom Tugendhat - 7/1
The Tory chairman of the Foreign Affairs Committee, 48, has only been an MP for seven years but was the first to confirm he’d throw his hat in the ring.
The centre-right former Remainer has been a vocal critic of Boris Johnson's foreign policy - such as on Russian sanctions and the botched withdrawal from Afghanistan - and said recently he had made his position "clear to those who need to hear it".
The privately-educated son of a High Court judge has dual citizenship with France, where his wife is a judge, speaks Arabic, and voted remain in the 2016 Brexit debate. His family own a forest in Essone, near Versailles.
He served in Iraq as an intelligence officer with the Royal Marines and later became advisor to the governor of Afghanistan's Helmand Province.
Rishi Sunak - 9/1
The 42-year-old Chancellor nicknamed 'Dishy Rishi' by his admirers shot up the rankings since becoming an MP seven years ago. He was long seen as the frontrunner to succeed Boris Johnson as Britain's first PM of Asian descent.
But the former investment firm founder has slipped down the rankings after a serious of "out-of-touch" gaffes as the cost of living crisis bites.
It emerged his wife Askhata Murty, with whom he's 222nd on the Sunday Times Rich List with a combined £730m fortune, was paying £30,000 a year to use her non-dom status not to pay UK tax on her overseas income. She later U-turned.
A fan of posed photos on Instagram, the four-car-owner was widely mocked for promoting a temporary fuel duty cut using someone else's car. Cameras also captured the embarrassing moment he struggled to use his bank card to pay.
Despite his image, some moderate Tories still believed he was the best candidate - especially if it was a choice between him or Liz Truss. But it would be difficult for him to run when he, too, has been fined by police over Partygate.
Penny Mordaunt - 11/2
Back in Government since February 2020, the 49-year-old Trade Minister has kept her head down in the current scandal but is widely thought to hold ambitions for leadership.
The Royal Navy reservist has trodden a diplomatic path, supporting Brexit while opposing bids to oust Theresa May in 2018.
Related to both Angela Lansbury and Labour's first chancellor Philip Snowden, she was educated at a Catholic school, a drama school and Reading University.
Since becoming an MP in 2010 she has worked in a string of top jobs including Defence Secretary but was sacked from the Cabinet by Boris Johnson - only to be brought back at a more junior rank.
Ben Wallace - 10/1
The 52-year-old Defence Secretary, an MP since 2005, is respected by many Tories for his no-nonsense style - including weeping in an interview last year over the withdrawal from Afghanistan and hitting back at Putin's threats over Ukraine.
But his blunt manner could also cost him some advancement, such as in 2019 when No10 slapped him down for being caught on camera making remarks about Boris Johnson's prorogation of parliament.
The privately-schooled son of a soldier attended Sandhurst and served in Germany, Cyprus, Belize and Northern Ireland before entering politics in the early 2000s.
Nadhim Zahawi - 14/1
The 55-year-old had a remarkable life story before being named Vaccines Minister during Covid, then Education Secretary.
His Kurdish parents fled Baghdad when he was nine and he was educated at a West London comprehensive, then a private school before attending UCL and building up a lucrative business career. He co-founded pollster YouGov before being elected to Parliament in 2010, and had a lucrative career with the oil industry before he took a ministerial job.
In 2013 he promised to repay a bill for power at his stables which was funded by taxpayers.
Sajid Javid - 20/1
The Health Secretary was one of 10 leadership challengers in 2019. Boris Johnson made him Chancellor but the relationship quickly soured, with Mr Javid resigning in February 2020 after he was told to fire his advisers.
He was on the back benches for most of the pandemic before returning to the Cabinet as Health Secretary. The 52-year-old MP became an MP in 2010 and has since rose through the ranks after being close to ex-Chancellor George Osborne.
His father was a bus driver who arrived in the country in 1961 with £1 in his pocket and Mr Javid went to a comprehensive school in Bristol before studying economics and politics at Exeter University. He carved out a high-flying career in finance, working as a managing director at Deutsche Bank before entering politics. .
He came under fire in 2015 after the steel sector was battered by thousands of job losses but he jetted off on holiday to Australia with his daughter and also had to apologise in July 2021 for saying it was time to stop "cowering" from Covid.
Michael Gove - 25/1
Boris Johnson's ally turned rival has held a string of cabinet posts and is currently overseeing the PM's flagship levelling up agenda.
After saying he was unlikely to, Mrs Gove, 54, then stood again in 2019 before losing out at the final ballot to Jeremy Hunt and Mr Johnson. During his campaign he admitted to taking cocaine when he was in his twenties - despite criticising middle-class drug users.
He's broadly seen as a slick - if slippery - messenger for whichever government rules the day, and although allies insist he's said he wouldn't run again a few times, but that hasn't stopped him before.
Dominic Raab - 25/1
The Deputy Prime Minister, 48, made it to the third round of the 2019 leadership contest after rising through the ranks as a Brexiteer.
The grammar school-educated former human rights lawyer, a karate black belt, became an MP in a Lib Dem target seat in 2010 and previously served as Brexit Secretary and Justice Secretary. He gained praise for deputising for Mr Johnson when the PM was hospitalised with Covid in 2020.
Mr Raab has made some controversial statements in the past, including as being moved from being Foreign Secretary after the disastrous withdrawal from Afghanistan, while he holidayed in Crete insisting the "sea was closed".
He once branded feminists "obnoxious bigots" and put out a pamphlet in 2011 that suggested exempting small firms from minimum wage laws for workers under 21. And he sparked fury in 2017 by saying most food bank users are not "languishing in poverty". When a disability activist told him "people are dying" under Tory austerity, he described her calls for cash as a "childish wish list".
Mark Harper - 33/1
The 52-year-old MP since 2005 had an abortive leadership run in 2019 in which the most exciting moment was saying he'd back the big cat in a fight between a lion and a bear.
Since then the Covid Recovery Group co-chief become a darling of lockdown rebels and one of the ringleaders among right-leaning Tory backbenchers who are discontented with the PM's leadership. But he's told friends he is unlikely to throw his hat in the ring.
Priti Patel - 33/1
To her admirers the 50-year-old MP is the ultimate Tory success story, inspired into politics by Margaret Thatcher after being raised by a Ugandan-Indian family in London and moving from PR into politics. To her critics she is a hardline right-winger who has led repeated attacks on refugees and the right to protest while Home Secretary.
An MP since since 2010, she was forced out as Theresa May's Trade Secretary in 2017 for holding off-the-books meetings during a holiday to Israel, which it was claimed broke the Ministerial Code. She was accused again of breaking the Code over bullying claims but exonerated by Boris Johnson, who overturned an ethics advisor's recommendation.
Her failure to stem the numbers of people crossing the Channel in small boats, including with a legally contentious plan to force them to Rwanda, could count against her with Tory MPs, but she is said to be considering a leadership bid this time around.
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