Now-former British Foreign Secretary Boris Johnson waves as he leaves Downing Street on June 28, 2018.Toby Melville / Reuters

For a while, it seemed nothing could bring down Boris Johnson. Despite a long history of challenging U.K. Prime Minister Theresa May’s authority—and an even longer history of diplomatic gaffes—the British foreign secretary proved himself seemingly immune to dismissal.

That is, until he decided to dismiss himself. Citing disagreements over Brexit, Johnson resigned from his post on Monday, following the high-profile resignation of U.K. Brexit Secretary David Davis the day before. Their departures mark the sixth and seventh walk-outs from May’s cabinet in less than a year, and come at a critical juncture in the U.K.’s ongoing negotiations with the European Union over its imminent exit, which will take place in less than nine months.

The back-to-back departures of two of the highest-ranking Brexiteers in May’s cabinet signal a deep disapproval of the prime minister’s Brexit plan, in which the U.K. would pursue a closely aligned customs relationship with the EU after it leaves the bloc. The envisioned relationship is so close as to render Brexit almost meaningless, critics say. Davis, in his resignation letter, warned that May’s proposal “will leave us in at best a weak negotiating position, and possibly an inescapable one.” And Johnson, in his resignation letter, wrote that “Brexit should be about opportunity and hope. That dream is dying, suffocated by needless self-doubt. … We appear to be heading for a semi-Brexit.” Johnson has also reportedly likened defending the plan to “polishing a turd.”

Such a comment was quintessential for a leader like Johnson, who was perhaps Britain’s least diplomatic diplomat. Johnson boasted a proclivity for gaffes, ranging from the amateurish (he needed to be reminded that reciting a poem about British colonial rule during a visit to Burma probably wasn’t the best idea) to the outright offensive (he once joked that the northern Libyan city of Sirte could become “the next Dubai” if they could “clear the dead bodies away”) to the hazardous (the Iranian government seized upon erroneous comments Johnson made about a jailed British-Iranian aid worker to extend her prison sentence). He has been a vocal critic of the prime minister, whose favored Brexit plan he called “crazy.” He has even suggested Donald Trump could do the job better. “I have become more and more convinced that there is a method in his madness,” Johnson said last month at a private dinner. “Imagine Trump doing Brexit. He’d go in bloody hard … There’d be all sorts of breakdowns, all sorts of chaos. Everyone would think he’d gone mad. But actually you might get somewhere.”

But despite his flagrant disloyalty to May and his gaffe-strewn tenure, Johnson remained seemingly impossible to fire. One reason for this is Brexit: Johnson emerged as the face of it during the 2016 campaign. Another reason has to do with the overall volatility of May’s government this past year. The prime minister could hardly afford to lose yet another cabinet minister—let alone two. And while Johnson may have proven himself brash and unpredictable at times, perhaps the prime minister reasoned that he would be easier to control within the government than outside it. After all, Johnson has hardly made his own leadership ambitions a secret. Now that he’s out from under May’s government, he may seek to unseat her at the top of it.

A leadership challenge isn’t entirely out of the question. It would only require 15 percent of May’s Conservative party (48 lawmakers) to call for a vote of no confidence in the prime minister. If the vote were to pass, May would have to resign, triggering fresh leadership elections. But it may not come to that. In the wave of resignations thus far, the prime minister’s allies have flocked to her defense—and even those who oppose her seem to be calling for a change of policy, not a change in leadership. Davis, in an interview Monday with the London-based radio station LBC, reaffirmed that despite his disagreements over Brexit, he believes May’s position is safe. “I had to resign because this was central to my job. … I’d have to be the champion of the policy that I didn’t believe in,” he said, before adding: “I would be surprised if [a leadership contest] is precipitated and if there is, I suspect she’d win it.”

In many ways, Johnson’s exit epitomizes his time in government. His nearly two-year tenure as foreign secretary was defined by unpredictable buffoonery. Not only has Johnson chosen to resign at a critical point in Brexit negotiations, but his exit is also timed with what already promises to be a crazy week for the U.K. One woman has died after a resurgence of Novichok poison in the English city of Salisbury, the NATO summit kicks off in Brussels on Wednesday, and Trump’s highly anticipated visit to the U.K. comes the day after that. It’s quite a week to be without a foreign secretary.

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