Cameron said he would step down on Wednesday, opening the way for May to take the keys to 10 Downing Street far sooner than anyone had expected.
“I’m delighted that Theresa May will be the next prime minister. She is strong, she is competent, she is more than able to provide the leadership that our country is going to need in the years ahead, and she will have my full support,” Cameron said.
The race to succeed Cameron was supposed to last through the summer — a slow-motion transition after Cameron’s political gambit failed when his pro-E.U. side lost in last month’s referendum.
The domino-style spectacle Monday was just the latest twist in a British political season that has been marked by constant surprise and upheaval.
As May takes over, she will be under pressure to trigger the country’s withdrawal from the 28-nation European Union.
The 59-year-old May will take office having never been voted into the job by anyone beyond lawmakers in the ruling Conservative Party. She will be the first female prime minister in Britain since Margaret Thatcher stepped down in 1990.
Cameron said he would chair his last cabinet meeting Tuesday and would attend Prime Minister’s Questions in the House of Commons on Wednesday for a final time as the nation’s leader, six years after he took the job.
“After that, I expect to go to the palace and offer my resignation, so we will have a new prime minister in that building behind me by Wednesday evening,” he said, standing in front of 10 Downing.
In brief remarks in front of cheering Conservative lawmakers outside Parliament, May promised to “steer us through what will be difficult and uncertain political and economic times.”
Leadsom’s sudden withdrawal appeared to have caught May’s campaign team — and the rest of British politics — off guard.
Leadsom, a relative unknown, had advocated for a British exit from the European Union. She came under intense criticism over the weekend after suggesting to the Times of London that motherhood would make her a better fit for prime minister, and she later told the Daily Telegraph that the pressure had been “shattering.” She did not mention the controversy in her remarks Monday.
May, the country’s home affairs secretary, had campaigned for Britain to stay in the European Union. But the no-nonsense May has repeatedly said that Britain cannot ignore the outcome of the June 23 referendum, in which 52 percent of voters opted to leave the E.U.
“I couldn’t be clearer: Brexit means Brexit, and we’re going to make a success of it,” she said at a campaign rally Monday morning, before Leadsom quit the race.
The key question now is timing.
May had earlier suggested that the country would wait until next year to trigger its departure. But with European leaders and pro-Brexit politicians pushing for earlier action, she could find that her hand has been forced.
Cameron’s loss in the referendum prompted him to tender his resignation.
The winner of the leadership contest was supposed to take over from Cameron shortly after the announcement of results on Sept. 9. But Leadsom’s decision to drop out obviated any need for a vote by the Conservative Party’s membership.
“In some ways, given the urgency of the economic and political situation the country is facing, it may have been the best thing to do for the sake of the country and the party,” said Tim Bale, professor of politics at London’s Queen Mary University.
Bale said that although the campaign was only days old, Leadsom had already shown that she would “have difficulty coping with the top job in British politics.”
Although another candidate could have conceivably been named to the ballot, there appeared to be no appetite for a summer-long contest involving a vote of the Conservative Party’s 150,000 grass-roots members. May had been a strong favorite to win, having secured a majority of votes among Tory lawmakers last week.
In announcing her decision in front of a dark-brick townhouse in central London, Leadsom endorsed May to take the job and argued that her rival should be allowed to take over as soon as possible. Leadsom said her departure from the race will allow the country to move forward with its Brexit plans.
“A nine-week leadership campaign at such a critical moment for our country is highly undesirable,” she said, adding that “business needs certainty.”
Michael Gove, the justice secretary who finished third in last week’s winnowing of candidates, also endorsed May on Monday. So did Boris Johnson, the former London mayor and a one-time Leadsom backer.
“It is vital that we respect the will of the people and get on with exploiting new opportunities for this country,” Johnson said in a statement, referring to the E.U. vote.
The sudden shift in the leadership race coincides with a visit to New York by Britain’s finance minister, George Osborne, in efforts to calm global investors uneasy over Britain’s plans for an E.U. break.
The push to quickly bring in a new prime minister also came as the opposition Labour Party continued to be mired in infighting. Angela Eagle, a former top deputy of party leader Jeremy Corbyn, announced Monday that she would challenge Corbyn for his job.
The leftist Corbyn has already lost a confidence vote among Labour members of Parliament, but he has refused persistent calls to step aside.
Dissidents within Labour, including Eagle, have argued that he was only an ambivalent campaigner for “remain” in the E.U. referendum and is ill-equipped to lead the party in a general election if the Conservatives decide to call one in order to renew their mandate.
The Conservatives, also known as Tories, won a majority in last year’s election, which is why they do not necessarily need to call a fresh vote in order to appoint a new prime minister. But both Labour and the Liberal Democratic Party on Monday called for a new election before the next scheduled vote, in 2020.
“Tories now have no mandate,” tweeted Tim Farron, leader of the centrist Liberal Democrats. “Britain deserves better than this.”
May has said that she would not call a new election as prime minister. But she had also said before Monday that she thought it was important to give voters a choice, even if balloting was open only to Conservatives.
Before the referendum, May was seen as a relative long-shot for prime minister, often rating mention for the job only behind Johnson and Osborne. But as better-known candidates were knocked out, May benefited from having kept a low-profile during the referendum campaign. That positioning has allowed her to campaign as a unity candidate capable of bringing back together the party’s warring “leave” and “remain” factions.
Karla Adam contributed to this report.