LONDON — Prime Minister Theresa May of Britain was battling to save her government Monday after her foreign secretary quit over Brexit, deepening a mood of crisis just eight months before the country is due to leave the European Union.
Foreign Secretary Boris Johnson was the second minister to leave her Cabinet within 24 hours as May pushed ahead with a proposal that would keep Britain more closely tied to the European Union than hard-line conservatives want.
Just last week, she appeared to have won the full Cabinet’s agreement on keeping Britain’s economy closely anchored to the European Union. But the resignations reopened speculation about a challenge to her leadership, something that May’s spokesman said she would fight.
But with the Brexit supporters in the party in full revolt, Conservative insiders predicted further resignations unless May drops her plan.
The turmoil comes days before a scheduled visit by President Trump, a champion of the kind of sharp break with the European Union that May has deemed unworkable. She is nevertheless expected to seek assurances from Trump that the United States is ready to enter negotiations on a bilateral trade agreement.
Yet, in recent weeks, several major British employers have issued warnings over the risks of Brexit. Most prominently, Jaguar Land Rover said that a chaotic Brexit deal would threaten to derail more than $100 billion worth of investment plans in Britain and force the closure of some factories.
Airbus and BMW also questioned whether they could continue to keep manufacturing facilities in the country under those conditions.
The public face of the 2016 campaign that persuaded Britons to quit the European Union, Johnson on several subsequent occasions had appeared to undermine May’s strategy. In comments that were recently leaked, he described her government as lacking “guts,’’ unfavorably comparing the prime minister’s negotiating style to that of Trump’s.
After the surprise resignation of David Davis, Britain’s chief negotiator in withdrawal talks with the European Union, there was an ominous silence Monday morning from Johnson, who was scheduled to host a diplomatic meeting in London to discuss the western Balkans.
Then, around 3 p.m., May’s office issued a statement that said simply: “This afternoon, the prime minister accepted the resignation of Boris Johnson as foreign secretary. His replacement will be announced shortly. The prime minister thanks Boris for his work.’’
The pound dropped against the dollar amid news of the resignation, and Conservative lawmakers appealed to their colleagues not to demand a confidence vote in May’s leadership.
Such a move could be set off by 48 of her party’s lawmakers — although it would take many more to dislodge her. Earlier, Davis told the BBC that he was not encouraging a challenge to May and ruled himself out as a contender if there were one.
But the resignation of Johnson renewed the debate just as May was hoping that she had restored some stability to the government by announcing that pro-Brexit lawmaker Dominic Raab would replace Davis.
Britain faces a deadline of March 29 to reach a deal with the European Union.
Addressing Parliament on Monday, May said the options presented so far by EU negotiators were unacceptable to Britain.
“If the EU continues on this course, there is a serious risk it could lead to no deal and this would most likely be a disorderly no deal,’’ she said. “A responsible government must prepare for a range of potential outcomes.’’
As a result, she said, the Cabinet agreed Friday to step up preparations for such an outcome, although she acknowledged that a sudden, hard exit without any agreements on trade, customs, or migration “would have profound consequences for both the UK and the EU,’’ and should be avoided.
The resignation of Davis, who was among the members of the Cabinet demanding a more complete break from the European Union, a so-called hard Brexit, revealed the intensity of the split in the Cabinet, although he did not appeal to other ministers to follow him.
Davis said that he could not accept the approach that May demanded in the meeting with top officials Friday, contending that Britain was giving away too much too easily in negotiations with Brussels and that he was leaving his job because he could not, in conscience, argue for the Cabinet’s Brexit position in public.
Other members of May’s Cabinet have been arguing for a “soft Brexit,’’ which would seek to maintain economic stability by keeping closer ties to the European Union.
Davis specifically cited concerns about any deal that would leave Britain in a customs union and the single market. “The general direction of policy will leave us in, at best, a weak negotiating position, and possibly an inescapable one,’’ he wrote in a letter to the prime minister that was released publicly. “The Cabinet decision on Friday crystallized this problem.’’
Davis acknowledged that there were no guarantees of what would happen after Britain leaves the bloc, but he said that May’s strategy meant that his position as chief negotiator was untenable.
May disputed Davis’s assessment of the situation, saying that whatever deal is reached would “undoubtedly mean the returning of powers from Brussels to the United Kingdom.’’
