Boris Johnson brought Britain to the precipice. And now, shockingly, he’s just going to walk away.

At a London press conference in which he was expected to announce his candidacy to lead the ruling Conservative Party, the former London mayor stunned the British political world by announcing that he will not run. “Having consulted colleagues, and in view of the circumstances of Parliament, I have concluded that person cannot be me,” he said. “That person” would be the prime minister of the country, charged with overseeing negotiations to take Britain out of the European Union—precisely what Johnson has urged for months, as one of the most prominent leaders of the “Leave” campaign.

His refusal to see the campaign through to the end will only harden suspicions that he is the proverbial dog who caught the car. He never intended Leave to succeed, the story goes, and was only using the Brexit campaign to build his public profile as a more conservative alternative to outgoing Prime Minister David Cameron. His decision to scurry for the exits could be read as a sign that he views the job of presiding over Brexit as a thankless dead end.

But there may be internal party dynamics at work as well. Earlier this morning, Johnson’s ally in the Brexit campaign, Michael Gove, announced that he would stand to be Conservative Party leader. “I have come, reluctantly, to the conclusion that Boris cannot provide the leadership or build the team for the task ahead,” Gove said. He is to face Home Secretary Theresa May, who advocated to “Remain” but nonetheless said she would oversee “a sensible and orderly departure from the European Union” as prime minister.