Prime Minister Theresa May's decision to step down on June 7 has fired the starting gun for a Conservative Party leadership race that could redefine Britain's exit from the European Union.
Here's a look at some of the possible candidates in what could be a bitter and dramatic contest.
Boris Johnson - Boris Johnson, or "Boris" as he's known to just about everyone in politics, as a child wanted to be "World King". No surprise, then, that he has confirmed he will run to be British prime minister. The 54-year-old quit Cabinet in protest at May's Brexit compromise plan last year, and has been railing against her "surrender" ever since in well remunerated columns for the Daily Telegraph.
His role in the Brexit referendum of 2016 was decisive and he's popular among grassroots activists. He's also built up the biggest war chest.
Johnson was famous for comedy appearances on TV before becoming mayor of London in 2008. In May's government, he was a foreign secretary prone to gaffes - some of them serious. And his inconsistency enrages critics: The day after he invoked the spirit of Moses to demand May deliver freedom from the EU, he capitulated and indicated he would back her deal - as long as she resigned.
Johnson is loathed in Europe, where he's famous for shaping British cynicism toward the EU during the 1990s through his work as a reporter in Brussels. He wrote stories that he cheerfully admits stretched credibility.
Dominic Raab - Dominic Raab, 45, had a low public profile before succeeding David Davis as Brexit secretary in July 2018. Following a return to the backbenches having rejected May's draft deal, Raab has concentrated on selling his backstory and setting out his vision for the country focused on boosting opportunity.
His determination is a key trait: A karate black belt, he trained and fought so hard he had to have a hip replaced in his mid-thirties. He's also picked fights in Parliament, and is the kind of clever lawyer who doesn't mind telling people they're wrong.
But he's also been a conciliator, and is probably the only member of Parliament to have both lived on an Israeli kibbutz and studied at Ramallah University. He's worked for Dominic Grieve, now the leading Tory pro-European, and arch-Brexiteer David Davis. The son of a Jewish Czech refugee and married to a Brazilian Catholic, he defies easy categorisation: sometimes blunt, sometimes charming.
Penny Mordaunt - Penny Mordaunt is known for being a good sport after appearing on television diving competition "Splash!" - donning a swimsuit to earn money for charity in her district. A Royal Navy reservist and daughter of a paratrooper, Mordaunt was the first woman to serve as armed forces minister and entered the Cabinet as international development secretary last year. She was promoted to Defence Secretary in May.
A former magician's assistant, Mordaunt, 46, made headlines in 2014 when she used a parliamentary speech on poultry welfare laced with innuendo to settle a bet with some Navy comrades. She also drew laughter from lawmakers of all parties when she highlighted the inadequacy of women's training in the military. "I felt that the lecture and practical demonstration on how to care for the penis and testicles in the field failed to appreciate that some of us attending had been issued with the incorrect kit," she said.
Mordaunt has marked euroskepticism in her favor, and her insistence that British foreign aid spending should be accountable to UK officials rather than international charities is popular among grassroots Tories. But her feminist credentials were undermined by her refusal, as equalities minister, to answer questions about transgender issues on the popular parenting website, Mumsnet.
Michael Gove - In 2016 Michael Gove, 51, was the backstabbing traitor in newspaper cartoons after he withdrew his support from long-time friend Boris Johnson to seek the Tory leadership himself.
After a stint on the backbenches, he was rehabilitated as an unexpectedly cuddly environment secretary, banning puppy-farming and pursuing a war on plastics. Considered to be more of a vision than details man, it's been argued he's too bad with numbers ever to be Chancellor of the Exchequer.
Gove's a long-time Brexiteer, unlike other more recent converts, which will satisfy the Tory grassroots. His public loyalty to May, and a House of Commons speech ridiculing Labour leader Jeremy Corbyn, have put him in poll position as a unity candidate among Tories, though he's a divisive figure nationwide.
Jeremy Hunt - Jeremy Hunt was the longest-serving health secretary in the history of the state-run National Health Service, despite an attempt by May to demote him. His tenure saw the first industrial action by junior doctors in 40 years, but he also convinced the premier to put 20 billion pounds ($26 billion) of extra funding into the institution-a gamble designed to prevent Labour securing easy votes over what many Britons consider a national treasure.
Now foreign secretary, the herbal tea-drinking top diplomat is a polite multimillionaire and a marked contrast to his gaffe-prone predecessor Johnson. Even so, ardent Tory Brexiteers may need more convincing of his euroskeptic credentials as Hunt, 52, campaigned to stay in the EU before announcing he'd changed his mind. He could emerge as the only candidate able to stop Johnson-if his supporters don't switch to his younger rival, Health Secretary Matt Hancock.
Sajid Javid - Son of a Pakistani immigrant bus driver, Sajid Javid is the first ethnic minority home secretary in the law-and-order post's history. A Muslim who is pro-Israel and socially liberal, Javid, 49, has been vocal on antisemitism, and also publicly condemned as "sick Asian pedophiles" the convicted members of a child sexual abuse gang who were mainly of Pakistani origin.
He's also distanced himself from a previous home secretary - his boss, Theresa May -particularly taking a less hardline approach to immigration. Fiscally tough and intellectually euroskeptic, Javid's positions are popular among rank-and-file Tories. A reluctant Remainer in the 2016 referendum campaign - partly out of loyalty and partly over economic fears -he has since moved firmly in the pro-Brexit camp, opposing a customs union with the EU.
Andrea Leadsom - Andrea Leadsom, 56, stood for the Tory leadership when former premier David Cameron resigned after the 2016 referendum, reaching the run-off against May. But she had to pull out after she suggested having children made her a better candidate than her rival. In media interviews, May had talked about her desire for children but said she and husband were unable to conceive.
May gave Leadsom a Cabinet position as environment secretary. She was shifted to Leader of the House of Commons in 2017, a position she held until May 22, when she quit over the premier's latest concessions on Brexit.
Though a prominent Euroskeptic, Leadsom-who worked in financial services before entering Parliament-backed May's blueprint for leaving the EU, and had been supportive of May until the premier offered Parliament a chance to vote for a second referendum.
She's gained fans among MP colleagues for her spats with House of Commons Speaker John Bercow, who many Tories accuse of anti-Brexit bias. Her resignation this week over May's Brexit strategy will do her chances no harm among Tory grassroots members.
Liz Truss - After growing up in a left-wing household in the northern county of Yorkshire, as a youngster Truss rebelled and joined the Tories. In the Thatcherite tradition, pro-Brexit Truss advocates de-regulation and hard work, and was co-author of a 2012 book claiming British workers are among the world's most idle.
As justice secretary in 2016, Truss, 43, came under fire for failing to defend the independence of the judiciary after a tabloid newspaper dubbed high court judges the "Enemies of the People" for ruling Parliament should be consulted before triggering the Brexit process.
She is also known for some bizarre political interventions, and for innuendo-laden jokes about sausages. A 2014 speech to the Tory annual conference went viral after she hyperbolically declared, "We import two thirds of our cheese. That. Is. A. Disgrace."
Currently chief secretary to the Treasury, she's skilled, illustrating a higher employment rate using children's book character Winnie-the-Pooh.
Matt Hancock - Having enjoyed a meteoric rise to become health secretary, 40-year-old Matt Hancock will be urging colleagues-as in the Queen rock hit he sings at karaoke-"Don't stop me now."
But Hancock's centrist politics mean he'll need to prove his pro-Brexit stance to colleagues and grassroots Tories. In an interview in April he said he still disagreed with the referendum result but would respect it because it's what the country voted for.
As a champion of new technology, Hancock was ridiculed for becoming the first MP to have his own personal app, but he shrugged it off, in-keeping with his well-established confidence in his own ability. On becoming a junior minister in 2012 at the age of 33, he defended his youth by comparing himself to former premiers Winston Churchill and William Pitt.
The hyperactive Hancock is the only modern-day lawmaker to have both won a horse race as a jockey and played cricket in the Arctic, and his Instagram account shows him running, playing with his dog, Hercules, and shaking hands with foreign dignitaries including French President Emmanuel Macron.
David Lidington - May's de facto deputy for the past 16 months is little known to the British public at large, but he's quietly risen to become one of the most powerful people in government.
He sits on almost all of May's Cabinet committees and was a key figure in the prime minister's efforts to find a Brexit compromise with the opposition Labour Party. He described the role in the Spectator magazine last year as like a man spinning plates. "Every now and then the PM gives me another plate and I have to keep that going as well."
The consummate party loyalist, Lidington, 62, is popular in Westminster for his politeness, calm demeanor and consensual approach. In Parliament since 1992, he served as Europe minister for six years in David Cameron's government, and has been one of May's staunchest allies. He's seen as a Remainer, though, which lowers his chances of being accepted by Euroskeptic Tories.
Lidington is more often talked about as a potential caretaker to steward the party through a leadership election, though in practice - as when Cameron resigned in 2016 - the incumbent has stayed through the succession process. Lidington has also indicated he's not interested in the job, saying working closely with the prime minister does "cure you completely of any lingering shred of ambition to want to do that task."
Amber Rudd - Amber Rudd, 55, returned to the Cabinet as work and pensions secretary in November, just over six months after being forced to quit as home secretary for misleading MPs over immigration targets-a charge for which she was largely absolved.
One of the most high-profile pro-EU members of Cabinet, Rudd-who has a wafer-thin majority of 346 in her southeast England constituency-has threatened to quit if a no-deal Brexit becomes government policy. That stance makes her an unlikely winner-Rudd has spoken wistfully about a modernizer becoming Tory leader again-but she could become king maker by persuading supporters to back another candidate.
Rudd is one of a group of Tory MPs, including Cabinet minister David Gauke, who launched a caucus in Parliament this month pledging to pursue economic and social responsibility through "one-nation Conservatism."
"Any new candidate is going to have to measure their Brexit policy against our values," Rudd told the BBC.