Here’s How a New U.K. Prime Minister Will Be Selected

British Prime Minister Boris Johnson’s premiership is coming to an end, he announced July 7, as a wave of resignations in his cabinet left his position as leader untenable.

Sexual misconduct allegations made against a senior lawmaker in Johnson’s government was just the latest in a series of scandals to strain the leader’s relationship with his party. After at least 50 lawmakers and government officials resigned in protest over a 48-hour period, Johnson said last week that he would resign but remain until his party has chosen a new leader.

Below, what happens next, and how U.K. leaders are chosen:

Read more: Boris Johnson Has Resigned. Here’s How He Lost Britain’s Government

How long will Johnson stay?

The next prime minister will be announced on September 5, once the Conservatives select a new party leader. Because the Conservative party has a majority in the U.K. parliament, the winner of the party leadership contest will automatically become prime minister. Johnson’s successor is likely to take over the next day, on September 6.

How is the new Conservative leader selected?

Under usual circumstances, British prime ministers are chosen in a general election held every five years. Instead of voting for the nation’s leader directly, as is the case in presidential electoral systems, the public chooses between delegates of each party to represent their local area, known as a constituency. The party that wins the most constituencies wins the election, and the leader of that party typically becomes the prime minister.

The Conservatives have a strong majority in parliament with 358 of 650 seats, after winning the 2019 general election under Johnson’s leadership.

Party leaders are chosen by an internal process normally in advance of a general election, or in the case that a leader steps down or is forced out. To take part in the race, a Conservative member of parliament needs to be nominated by at least 20 colleagues. Current favorites to follow Johnson include former finance minister Rishi Sunak and international trade secretary Penny Mordaunt. A winner is selected from the nominated individuals in a two-stage process.

Read more: Who Could Replace Boris Johnson As U.K. Prime Minister?

First, MPs whittle the candidates down in a series of secret ballots, whereby the candidate with the fewest votes is eliminated at each round until two are remaining.

In the second stage, card-carrying grassroots party members vote on the final two candidates. (It’s possible that it never goes to a final run-off, as was the case in 2017, after May’s opponents were eliminated or eventually withdrew.) Anyone in the U.K. can become a member of a party, provided that they pay a membership fee—which is £25 ($30) for the Conservatives. The Conservative party has around 200,000 members. This means that the final decision to select Johnson’s successor will be made by roughly 0.29% of the British population.

Grassroots party members haven’t always been able to influence the outcome of leadership contests. In 1998, the Conservatives decided to hand some of the power over to the rank and file, partly to embolden grassroots supporters and reverse decades of plummeting membership numbers. Although the new process helps to decentralize party politics, low membership levels mean that Conservative voter values may not be accurately represented by card-carrying members.

The timeline for choosing a new leader

The timeline for the contest includes three rounds of voting in quick succession from July 13 to July 18. The deadline for selecting the final two candidates is July 21.

Then, the decision will go to card-carrying Conservative party members. This voting process will take longer, with the winner announced on September 5.

What does this mean for British voters?

There is no fixed date for the next general election, but it is expected in late 2024 or early 2025. Leaders of the Conservative party can resign at any point, or be forced out by a vote of no-confidence from MPs. (Johnson survived a confidence vote by 211 votes to 148 on June 6, and his predecessor Theresa May twice, first by 200 votes to 117 in December 2018 and again by 325 votes to 306 in a parliamentary-wide challenge in January 2019.)

In any case, a new Conservative leader may decide to call an early general election to bolster their mandate among the general public. This avenue is a gamble, however. Although Johnson won a large majority after the December 2019 election, allowing him to push through his Brexit agenda, May’s decision to call a snap election in 2017 resulted in the Conservative party losing its parliamentary majority—and contributed to the Brexit impasse that led her to resign in June later that year. (May took over after her predecessor, David Cameron, resigned in the wake of U.K. voters opting to back “Leave” in the June 2016 Brexit referendum.)

An early election appears out of the question today. The Labour party attempted to call a no-confidence vote in both Johnson and the government in a bid to trigger a general election. But the Conservative-majority U.K. parliament blocked the vote. “As the prime minister has already resigned and a leadership process is underway we do not feel this is a valuable use of parliamentary time,” a government spokesperson said, according to The Guardian.

This story was updated on July 13 to reflect new developments in the leadership race.