Prime Minister Theresa May of Britain has announced that she will step down as the Conservative Party leader on June 7, bringing into the open a party leadership struggle that has been underway on the sidelines for months.
But deep divisions within the party and the nation over Britain's withdrawal from the European Union proved fatal to May's leadership, and it is not clear that a successor would fare any better.
Anyone seeking the job first has to be nominated by two members of Parliament. If there is only one candidate, he or she automatically becomes the new leader. If there are more than two, lawmakers vote among themselves to narrow the field to two candidates, who then are put to a vote by the 120,000 mostly white, mostly aging Conservative Party members. The party said it expected to begin the nomination process in the week of June 10, after May steps aside, and to complete the process by the end of July.
Here are some potential successors seen as having the best chance to become head of the Conservative Party and, eventually, prime minister.
Johnson, 54, the former foreign secretary and one of the most outspoken critics of May's Brexit plan, is one of the most polarizing figures in British politics but seen by some hard-line Brexit supporters as a good choice.
He was a figurehead in the campaign to leave the European Union, and since the 2016 referendum has pushed for a hard split with the bloc. This stance regularly put him at odds with May as she fought for a deal that would, supposedly temporarily, maintain relatively closer ties to Europe, and he regularly undermined her efforts to sell her deal to Parliament.
On Friday, that history seemed distant immediately after May's announcement. In a statement posted on Twitter, he thanked May for her "stoical service to our country and the Conservative Party" and urged lawmakers to heed her call to deliver Brexit.
Scotland's first minister, Nicola Sturgeon, was quick to call him out as hypocritical.
Johnson first gained notoriety for his bombastic displays as mayor of London from 2008 to 2016, before returning to Parliament. He was one of the most prominent voices of the Leave campaign that urged Britain to vote for the country's exit from the European Union, and since the 2016 referendum has advocated a hard split.
Johnson served as foreign secretary in May's Cabinet, but resigned in 2018 in protest over her withdrawal strategy.