Britain’s Theresa May survives a challenge to her leadership, but her vision for Brexit remains in doubt

(Mark Duffy | UK Parliament via AP) Backdropped by members of the ruling Conservative Party, Britain's Prime Minister Theresa May, centre, stands as she speaks during the regular scheduled Prime Minister's Questions inside the House of Commons in London, Wednesday Dec. 12, 2018. May has confirmed there will be a vote of confidence in her leadership of the Conservative Party, later Wednesday, with the result expected to be announced soon after.

London • Lawmakers in Britain’s Conservative Party on Wednesday triggered a no-confidence vote against Prime Minister Theresa May, threatening her leadership as she struggles to secure a deal for Britain to leave the European Union.

May responded that she would not resign but would carry on with her vision for Brexit. She warned rebellious lawmakers that ousting her would not make getting a better Brexit deal any easier and would instead bring delay and confusion.

"I will contest that vote with everything I've got," said May, speaking outside her Downing Street residence. "I stand ready to finish the job."

The no-confidence vote involves only Conservative Party lawmakers and not the entire Parliament. If she is toppled as party leader, replacing the prime minister could take weeks. Changing leaders now, May warned, would "put our country's future at risk and create uncertainty when we can least afford it."

The vote on the prime minister's fate will take place Wednesday evening, with results announced by 9 p.m. local time.

May and her Brexit plan have been pummeled for weeks by members of Parliament, both from her own party and the opposition. But faced with the prospect of losing their leader in a no-confidence vote, a long string of top Tories publicly declared their support for her - suggesting that the prime minister could survive the day.

In an 11th-hour meeting with her backbench, May told Tory members that she would not stand for election before the public again.

George Freeman, a Conservative member of Parliament, revealed a "powerful and moving moment" as May told her fellow Tories that she has "listened, heard and respects the will of the party" and that once she delivers Brexit "she will step aside for the election of a new leader to lead the reunification and renewal we need." Delivering Brexit, however, could take months or, more likely, years.

If May prevails, her leadership will be secure from another challenge by party members for a year. If a large number of her fellow Conservatives vote against her, she may be pressed to resign. If a simple majority of Tory lawmakers vote against her, May would be removed.

The looming vote throws May's Brexit deal and Britain's future relationship with Europe into chaos.

In Brussels, European diplomats shook their heads in dismay. European leaders are frustrated that Britain appears hopelessly divided over Brexit.

"It's getting so messy and absurd that even the funny elements are tragic," said one senior E.U. diplomat who briefed reporters on the condition of anonymity.

May announced Monday that she was delaying a parliamentary vote on her deal, after she concluded that the accord faced a humiliating defeat in the House of Commons. May spent Tuesday meeting with Netherlands Prime Minister Mark Rutte, German Chancellor Angela Merkel and E.U. leaders, trying to concoct new concessions that might appease British lawmakers who oppose her Brexit withdrawal agreement.

For the Tories to challenge May, ostensibly their party leader, they needed to send at least 48 letters - equaling 15 percent of the 315 Conservative lawmakers - to Sir Graham Brady, the chairman of the 1922 Committee in Parliament.

Brady told the BBC that he informed the prime minister on Tuesday night that the threshold of 48 letters had been reached. May was "businesslike and keen to proceed as quickly as possible," he said.

Brady said the no-confidence ballot would take place Wednesday between 6 p.m. and 8 p.m. Votes will be counted "immediately afterward and an announcement will be made as soon as possible," he said.

For May to survive a leadership challenge, she needs a simple majority of Conservative lawmakers - 158 of 315 - to back her.

May advised her fellow Tories to look at the calendar. "The new leader wouldn't have time to renegotiate a withdrawal agreement and get the legislation through Parliament by the 29th of March," the date when Britain is set to leave the European Union, she said.

A new leader would have to seek delay, May said. "So one of their first acts would have to be extending or rescinding Article 50, delaying or even stopping Brexit when people want us to get on with it," she said, referring to the provision of the E.U. treaty that allows members to withdraw from the bloc.

The leader of Scotland, Nicola Sturgeon, expressed frustration with the political squabbling. She tweeted: "Today is a stark reminder that the UK is facing chaos and crisis entirely because of a vicious civil war within the Tory party. What a self-centered bunch they are. They all need to go, not just the PM."

Many Tories vowed to back May, though the actual vote on Wednesday evening is by secret ballot, so there is room for surprise.

Conservative lawmaker Geoffrey Cox tweeted that he would be backing the prime minister, adding: "This is no time for the self indulgent spasm of a leadership election."

Supporters include Foreign Secretary Jeremy Hunt and Home Secretary Sajid Javid.

Philip Hammond, the chancellor of the exchequer, called the Tory rebels who pressed for a no-confidence vote "extremists" and predicted that they would fail. He tweeted: "The Prime Minister has worked hard in the National interest since the day she took office and will have my full support in the vote tonight. Her deal means we leave the EU on time, whilst protecting our jobs and our businesses."

Tim Bale, a professor of politics at Queen Mary University of London, said that in practice, May would probably need to win by more than a simple majority to stay in power.

If she were to win by just a narrow margin, that would "indicate that so many of her MPs didn't want her," Bale said. "It would be morally difficult to carry on."

Bale also said that a new leader may not solve the Conservative Party's Brexit problems. "Is the problem actually the prime minister? The problem is what it has always been. Any deal that could pass muster with the E.U. won't pass muster with Tory Euroskeptics."

There is no shortage of fellow Tories who have suggested they might make fine replacements, if May is removed. Among the possible contenders are former Brexit secretary Dominic Raab and former foreign secretary Boris Johnson. Both men resigned their posts, saying they could not support May's Brexit deal because it kept Britain too closely aligned with Europe.

"Vassalage," Johnson called it.

Commentators were quick to draw comparisons to Margaret Thatcher, the original Iron Lady and Britain's only other female prime minister, who won a vote of confidence on the first ballot but resigned anyway in 1990. The party's rules were very different then. Now, a leader cannot be challenged by a rival - a contest is triggered by the 48 letters - and needs to win by only a single vote.

If May loses the vote, she could remain as a caretaker prime minister until another leader is found, a process that could take six weeks. If multiple candidates throw their hats in the ring, then Conservative lawmakers vote, with the candidate receiving the fewest votes removed. In the past, the voting has taken place on Tuesdays and Thursdays. Then, when two candidates are left, a vote is put to the wider grass-roots Conservative Party membership, which is more pro-Brexit than Parliament.

When David Cameron resigned as prime minister the morning after Britain's 2016 Brexit referendum, he stayed on as caretaker prime minister for three weeks until May replaced him in July 2016. In that leadership context, the field was whittled down from five to two candidates - May and Andrea Leadsom. Leadsom dropped out after she gave an interview suggesting she was the stronger candidate because she had children.

In Brussels, where preparations are underway for a summit of European leaders Thursday and Friday for which Brexit is only one issue among many, diplomats were measured in their reaction to the British drama. Many have long braced for a challenge to May's leadership, and although the British instability added to uncertainty surrounding the Brexit deal, several diplomats said there was little they could do to sway events in London.

If anything, the leadership challenge hardened resolve among the remaining E.U. nations to insist on an ironclad backup plan to preserve a border-free frontier between Ireland and Northern Ireland. Diplomats increasingly doubt they can rely on assurances from any British leader, because that leader could quickly be replaced.

European leaders are stepping up their planning for the chaos that would be created by Britain's crashing out of the E.U. with no deal in place at all. That could also lead to the imposition of border controls at the Irish border, meaning that both sides have motivations to solve the issue.

"We do not have any intention of further changing the withdrawal agreement," Merkel told the German parliament on Wednesday ahead of the summit. "That is the common position of the 27 member states."

Birnbaum reported from Brussels. The Washington Post’s Quentin Ariès in Brussels contributed to this report.