In the two years since a narrow majority of Britons voted to leave the European Union, the planning of the country’s actual departure has often looked like a disaster unfolding in slow motion. In the past few days, as an anonymous public servant, displaying the sangfroid for which British mandarins used to be famous, put it, “We have at least now reached the kinetic phase of the car crash.”

Prime Minister Theresa May—facing the thankless, and maybe impossible, task of fashioning a plan that would honor the result of the 2016 vote, unite her Conservative Party, garner acceptance from other European governments, and minimize the collateral damage to the British economy—has spent much of the past twenty-four months temporizing and fending off potential challenges to her leadership. On Friday, she finally acted, summoning her Cabinet to her official country house, which is known as Chequers, and demanding support for what she presented as the best available negotiating plan.

For about forty-eight hours, it appeared that May had succeeded in gaining unanimous backing for her proposal—but that proved illusory. On Sunday night, David Davis, the Secretary of State for Exiting the European Union, a specially created post, quit, saying that May was making too many concessions to the E.U. Hours later, two junior members of the government resigned, too. And then, on Monday afternoon, Boris Johnson, the old Etonian mop top who for the past two years has served as May’s far-from-entirely-loyal Foreign Secretary, joined the leaving party. In a public letter, he said that the Brexit “dream is dying, suffocated by needless self-doubt,” and suggested that May’s strategy amounted to leading the U.K. into a “semi-Brexit,” with the “status of a colony.”

Like his hero Winston Churchill, Johnson has a penchant for laying it on thick, as well as an all-consuming ambition. Early in his career, as a Brussels-based correspondent for the Daily Telegraph, he concocted all sorts of scare stories about the E.U. bureaucracy, including one claiming that the E.U. gauleiters were threatening to outlaw English sausages. After switching to politics and getting elected to the House of Commons, in 2001, Johnson made his mark as an articulate and socially liberal Conservative, a platform he used, in 2008, to become a fairly progressive and forward-looking two-term mayor of London. But after returning to Parliament, in 2016, he re-created himself again—this time as a pro-Brexit Little Englander—and in doing so he aligned himself with some of the most reactionary and xenophobic forces in the country.

Conspicuously lacking from Johnson’s resignation letter was any convincing, or even merely plausible, alternative to the Brexit strategy that May presented. This omission was no accident. As much as the hardcore Brexiteers huff and puff about May going soft and betraying the legacy of Henry VIII—who started the English Reformation rather than bowing to the will of a European authority, the Pope—they have presented no convincing answers to the challenges with which the Prime Minister and her advisers have been wrestling.

As May explained to the House of Commons on Monday, she is dealing with “the practicality of Brexit” rather than the dream. In the past few months, it has become increasingly clear that making a clean break with the E.U.—what the so-called hard-Brexit crowd is demanding—would wreak havoc on Britain’s economy. It would deprive businesses based in the United Kingdom of free access to the European market and to the extensive supply chains that many of them have in the E.U. For a time after the Leave vote, the scale of this problem remained partially obscured because many businesses maintained a diplomatic silence. But, more recently, a number of major manufacturers, including Airbus, BMW, and Jaguar Land Rover have intimated that, in the event of a hard Brexit, they would have no choice but to move their factories and investments out of the U.K.

The dilemma facing the May government is that to maintain the “frictionless” access to the E.U. that businesses are demanding, the U.K. will have to abide by some of the Union’s rules and regulations, even though it will no longer be a member. Norway has been living with such an arrangement for decades, and the system has worked pretty well. But Johnson and his supporters, who include many Conservative Party activists, regard going down this route as a betrayal of British sovereignty.

Actually, May’s pursuit of such a scenario is a belated, and still incomplete, recognition of political reality. In her speech, May confirmed that under her plan British companies that do business with the E.U. “will continue to operate to the E.U. rule book.” But she also claimed that the terms she is proposing would prevent European workers from moving freely to the U.K., abolish the jurisdiction of the European Court of Justice over British courts, end the annual payments that Britain makes to the E.U. budget, and give the British Parliament a veto over any new E.U. laws or rules that affect Britain.

These demands go well beyond the Norway model, and there is absolutely no guarantee that the E.U., which is keen to discourage other member countries from following the Brexit example, will agree to any of them. In return for unfettered access to the European market, Norway accepts the free movement of European workers across its borders. It is also subject to thousands of E.U. laws, and it pays hundreds of millions of dollars each year to some of the Union’s poorer countries.

Talks between Britain and the E.U. are scheduled to resume next week. Michel Barnier, the former French Foreign Minister who is leading the E.U.’s negotiating team, has publicly welcomed May’s proposal, but he stopped a long way short of accepting it. “We will assess proposals to see if they are workable & realistic in view of #EUCO guidelines,” he wrote in a tweet.

It also remains unclear whether May will still be in office to complete the negotiations. At Westminster on Monday, there was speculation that Johnson’s resignation presaged a challenge to the Prime Minister’s leadership of the Conservative Party. In 2016, after the Leave vote prompted David Cameron, the previous Tory leader and Prime Minister, to resign, Johnson toyed with running for the top job, but he backed out after deciding that he couldn’t win. (That was when May was chosen.)

On Monday, a spokesman for May told reporters that she would fight any leadership challenge rather than resign. Later in the day, she appeared at a meeting of Conservative M.P.s, who loudly cheered her. Allies of the Prime Minister expressed confidence that she had the votes to fight off any challenger, and even Jacob Rees-Mogg, a prominent hard-Brexit supporter, said that he didn’t think there would be enough support to force an immediate vote of confidence on May’s leadership.

But Rees-Mogg also warned that the battle inside the Tory Party was far from over, and he’s right about that. May already heads a minority government. With at least some Conservative M.P.s sure to side with Johnson and Rees-Mogg, it seems likely that she will have to rely on support from the opposition parties as she goes forward. “If the government plans to get the Chequers deal through on the back of Labour Party votes, that would be the most divisive thing it could do,” Rees-Mogg said, “and it would be a split coming from the top, not from the members of the Conservative Party across the country.”

On Monday night, another junior member of the government, an M.P. named Chris Green, resigned, saying, in a letter to May, “Brexit must mean Brexit.” That brought the number of resignations to five. But, however many resignations there are, the realities of Brexit will remain.