Here are 5 possible contenders to replace Boris Johnson as U.K. prime minister

LONDON — British Prime Minister Boris Johnson resigned as leader of the Conservative Party on Thursday.

He said he will stay on as prime minister while the party selects a new leader.

Given that the Conservative Party won the last election in a landslide, the country won't necessarily

Instead, next week, a small group of Conservative legislators inside Parliament

known as the 1922 Committee — will determine the rules for a new leadership

contest that will help select Johnson's replacement from among the 350 or so Conservative lawmakers.

Under the United Kingdom's parliamentary system, the winner of that Conservative Party contest will then become the new British prime minister.

Some senior figures in his party say even that will be unsustainable, given the dwindling number of people willing to work for him.

Others are already lining up to replace him. Party officials say they will announce the timetable for a leadership election by Monday.