British Prime Minister Keir Starmer is expected to decide soon whether he will step down from his position or face a leadership challenge from a political rival, Andy Burnham, who represents the country's Labour Party. 

Starmer has publicly vowed to stay in the post, but pressure is building as more and more Labour Party colleagues conclude his time is up. Expectation is growing that he will announce a timetable for his resignation as soon as Monday. That's the day Burnham will be sworn in as a lawmaker in the House of Commons after winning a special election last week.

Business Secretary Peter Kyle said Sunday that Starmer is "making time to reflect on the political realities, challenges and opportunities that he finds himself in."

"I know he is a prime minister who always puts his country first," Kyle told CBS News partner BBC News, though he called reports that Starmer will resign are "speculation."

Starmer is spending the weekend at Chequers, the country mansion used by British prime ministers, with his family. He gave no public hint about his decision, but shared a Father's Day message on social media.

"Being a dad is my greatest joy. Today, I'm thinking about my dad, and the father I am to my children because of him," he wrote on X.

If Starmer quits, he will be the sixth prime minister to leave office in the past 10 years, an extraordinary rate of churn for the United Kingdom.

Through internal elections, political parties in the U.K. can replace their leaders, including prime ministers, at any time. That can happen if enough members of a party lose confidence in a leader, even if no general election is held. U.K. law requires a general election to take place at least once every five years, but it also allows one to be called sooner than that by the government in power. If a prime minister is replaced, the reigning political party remains in charge of the government until a wider vote is held. 

Discontent with Starmer has been building for months, with Labour lawmakers desperate to reverse the government's decline in popularity since Starmer led the center-left party to a landslide election victory in July 2024.

He has struggled to deliver promised economic growth, repair tattered public services and ease the cost of living, and has been hamstrung by repeated missteps, including his decision to appoint Peter Mandelson, a scandal-tarnished friend of Jeffrey Epstein, as the U.K. ambassador to the United States.

Labour is losing liberal voters to the growing Green Party and facing a rising Reform UK, the Nigel Farage-led anti-immigration party that consistently leads in nationwide opinion polls.

Burnham, until this week the popular mayor of Greater Manchester, decisively won the seat of Makerfield in northwestern England in a special election held Thursday. He took almost 55% of the 45,510 votes cast, over 9,000 more than the Reform UK runner-up.

Now that he is a lawmaker, he's in a position to challenge Starmer for leadership of the Labour Party. Burnham's acceptance speech left no doubt that he wants to lead both the party and the country.

"Everyone knows that politics isn't working," he said. "Everyone can feel that the country isn't where it should be. Tonight could, just could, be the turning point."

It's unclear whether Burnham would face a coronation or a challenge if Starmer steps aside. Wes Streeting, who resigned as health secretary last month to protest Starmer's leadership, has said he will run in a contest if there is one.

Starmer congratulated Burnham on Friday, but insisted he would fight any attempt to oust him.

"I will run, I will stand," if there is a Labour leadership contest, Starmer said. "I've said repeatedly I'm not going to walk away from that."

But Charlie Falconer, a senior Labour member of the House of Lords, said Saturday that Starmer has "absolutely no authority" left.

"There should be an agreed transition process in which Andy and Keir cooperate as to when the handover should take place," he told the BBC.