AFTER HER proposed Brexit deal triggered a flurry of government resignations, Theresa May’s job is on the line. The British prime minister faces a potential leadership challenge. Speaking to a crowd of gawping journalists and curious tourists outside the Houses of Parliament on November 15th, Jacob Rees-Mogg (also pictured), an influential backbencher, demanded a confidence vote in the prime minister. He is not the only one to have done so. But how would Conservative MPs go about removing Mrs May? And how would they choose her successor?

Under the Conservative system, a confidence vote is triggered when 15% of Tory MPs send letters of no confidence to the chair of the 1922 Committee, which represents Conservative MPs in parliament. The party has 316 MPs, so 48 have to write in. All Conservative MPs may vote in the ballot, with the result dictated by a simple majority. This can happen quickly: in 2003, the confidence vote came only a day after it was triggered. If Mrs May wins, she stays on as leader. As an added bonus, another challenge cannot be launched for a year. If Mrs May loses, she would no longer be Conservative leader. Selecting a new leader would then involve two rounds. First, the candidates must win the votes of fellow MPs. The candidates stand against each other in consecutive rounds of votes, with the candidate in last place getting eliminated each time, until only two remain. These two names are then put forward to the estimated 130,000 members of the Conservative Party. They are the happy few who would have a direct say on Britain’s next prime minister.

Britain, then, can change prime minister without the bother of a general election. It is relatively common. Mrs May took over from David Cameron in this way. So did Gordon Brown, who succeeded Tony Blair as leader of the Labour Party and thus prime minister in 2007. The head of the largest political party is asked by the Queen to form a government however they ended up in that position.

Mrs May might discern some light in the gloom. It is one thing to muster 48 MPs fed up with the prime minister. But it is quite another to persuade 158 to vote against her, with no obvious successor in the wings. Another Conservative prime minister would face exactly the same problems as Mrs May: a divided party, a weak hand in Brussels and a split country. If Mrs May wins the no-confidence vote, her immunity from a future challenge would provide some political leeway. In that time, she may somehow push her deal—or a version of it—through Parliament. Her prospects and those of her party may look better in a year. But MPs may not want to find out. Those who are supportive of the prime minister in public may express a different view in the privacy of a voting booth.