UK leadership challenge: How does it work?

British Prime Minister Theresa May spent Monday touring Europe in an effort to save her Brexit deal. She returned on Tuesday to find lawmakers from her own party had triggered a leadership challenge. 

This week, May had canceled a planned vote on her divorce agreement with the EU, fearing a heavy defeat. The deal she had reached with Brussels had previously prompted several high-profile resignations from her Cabinet.

How this happened

A challenge can be triggered if 15 percent of the Conservative MPs write a letter to the chairman of the influential "1922 Committee" [the parliamentary group of all backbench Conservative lawmakers] demanding a vote of confidence in the leader. The party currently has 315 MPs, meaning 48 would have to submit a letter. Graham Brady, chairman of the 1922 committee, announced Wedensday that the threshold had been exceeded.

Who led the challenge?

Leading euroskeptic Brexiteer Jacob Rees-Mogg was among the first to call for a vote of confidence in mid-November. "It is of considerable importance that politicians stick to their commitments or do not make such commitments in the first place. Regrettably, this is not the situation," he wrote in his official letter.

Former cabinet minister Owen Paterson helped tip the balance on Wednesday. "It would be a travesty if the democratic verdict of the 2016 referendum – the largest in British history – were not delivered," he wrote. "Yet the Prime Minister's proposed 'deal' is so bad that it cannot be considered anything other than a betrayal of clear manifesto promises."

Does May have any support?

A number of high-profile members of her cabinet immediately pledged their support, including Work and Pensions Minister Amber Rudd, Foreign Secretary Jeremy Hunt and Home Secretary Sajid Javid.

What happens during a confidence vote?

All Conservative MPs can vote, either in favor of or against the leader staying on. May would need a simple majority to win. That would currently mean 158 votes.

What happens if May wins?

In the event of a victory, she remains in office and gets immunity from another formal challenge for a year. However, if she fails to win convincingly, May could decide to step down as party leader.

And if she loses?

May would then have to resign and is barred from standing in the ensuing leadership election. That process could take up to six weeks, during which time May would be expected to fill the role of caretaker prime minister. Her eventual successor would also become prime minister. A general election would not automatically be triggered.

Read more:Brexit deal: What Germany wants, what Theresa May can get