LONDON (AP) — The race to become Britain's next prime minister took a dramatic, unexpected turn Thursday as former London Mayor Boris Johnson — popular with the public and widely considered to be a front-runner — ruled himself out of contention after the defection of a key ally.
In a morning of political machinations and high-stakes treachery that had commentators reaching for Shakespearean parallels, Justice Secretary Michael Gove abruptly withdrew his support for Johnson and announced he would run for the Conservative Party leadership himself.
Johnson, a prominent campaigner for Britain's withdrawal from the 28-nation European Union, then told a news conference that the next Conservative leader would need to unite the party and ensure Britain's standing in the world.
"Having consulted colleagues and in view of the circumstances in Parliament, I have concluded that person cannot be me," he said to the astonishment of journalists and supporters.
The decision by Johnson, 52, is an unexpected twist in a political career that saw him serve as journalist, lawmaker and mayor, building a public profile on Latin quips, cycling and rumpled eccentricity, while nurturing a poorly concealed ambition to lead his country.
Johnson's decision to break with longtime ally Prime Minister David Cameron and back the "leave" side in Britain's EU referendum seemed to have paid off last week, when Cameron resigned after voters decided 52 to 48 percent to exit the bloc.
Cameron's resignation triggered a Conservative leadership race. By Thursday afternoon, the nominating period had ended, leaving five candidates: Home Secretary Theresa May, Work and Pensions Secretary Stephen Crabb, Energy Minister Andrea Leadsom and former Defense Secretary Liam Fox, in addition to Gove.
Conservative lawmakers will choose two finalists and then more than 100,000 party members select the winner by a postal ballot, to be announced on Sept. 9
The winner will become Britain's prime minister and play a vital role shaping the nature of its relationship with the EU after last week's Brexit vote ended the career of Cameron, whose bid to keep Britain in the continental bloc failed.
The bookies' early favorite is the 59-year-old May, who is seen by many in the party as a safe pair of hands as the country struggles to disentangle itself from the EU. Her six years as Britain's interior minister, considered one of the toughest jobs in politics, gives her credibility to deal with the EU on the issue of immigration, sure to be one of the thorniest topics in the exit talks.
"My pitch is very simple," she said at a campaign launch event. "I'm Theresa May and I think I'm the best person to be prime minister of this country.
"If ever there was a time for a prime minister who is ready and able to do the job from day one, this is it."
Although May had offered a tepid endorsement of Britain's place in the EU during the referendum campaign, she was clear that the results of the vote would be respected.
"The United Kingdom will leave the EU," she said, pledging to create a brand new government department devoted to negotiating Britain's "sensible and orderly" departure from the bloc.
Boosting May's chances was a last-minute falling out between her two leading competitors — Gove and Johnson — who had campaigned together to yank Britain from the EU.
Both men have been criticized since the referendum result was declared Friday for failing to lay out concrete plans for Britain's divorce from the EU.
Johnson addressed the issue in a Daily Telegraph column that seemed to say Britain would continue to enjoy most of the benefits of EU membership — a claim dismissed by European leaders as wildly unrealistic.
His bombshell decision not to run spurred a stream of allegations on Twitter from those who felt he led the country into the economic and political disaster of an EU exit and then sidestepped having to clean up the resulting mess.
Gove, who is liked within the party but less popular with the public, had long disclaimed any ambition to be Britain's leader. In 2012, he said he was willing to "sign a piece of parchment in my own blood saying I don't want to be prime minister." Asked if he would run earlier this month, he said: "Count me out."
Gove tried to explain the 180-degree switch in a statement Thursday, saying he had "wanted to help build a team behind Boris Johnson."
"But I have come, reluctantly, to the conclusion that Boris cannot provide the leadership or build the team for the task ahead," Gove said. "I have, therefore, decided to put my name forward for the leadership."
An email from Gove's wife, Daily Mail columnist Sarah Vine, obtained by Sky News, suggested that Gove should ensure he had specific guarantees from Johnson before backing the latter's bid. She added that influential right-wing media barons Rupert Murdoch and Paul Dacre "instinctively dislike" Johnson.
Gove's camp declined to comment on the missive.
Steven Fielding, professor of politics at the University of Nottingham, said Johnson "wasn't trusted enough by the people who really wield power in British politics — Rupert Murdoch and Paul Dacre."
Johnson remains a member of Parliament, and few would rule out an eventual return to front-line politics.
The opposition Labour Party is also is extreme disarray, with leader Jeremy Corbyn facing intense pressure to resign after losing a confidence vote and being on the losing side in the EU referendum. He has lost the support of the party's lawmakers but claims the rank and file still back him.
Corbyn is expected to face a formal leadership challenge in the coming days. He has faced heavy criticism for failing to campaign effectively to keep Britain within the EU.
Associated Press writers Gregory Katz and Raphael Satter contributed to this story.