EXPLAINER-Could UK PM Starmer be forced out after local election losses?

LONDON, May 8 (Reuters) - British Prime Minister Keir Starmer has vowed to carry on ​as leader ⁠after his Labour Party suffered heavy losses in local elections that ​have deepened doubts over his ability to govern.

Some critics inside the party have called for him to go. Here's what could happen next:

IS STARMER FACING A LEADERSHIP CONTEST?

Not ​at ‌the moment.

In addition to Friday's losses, Starmer's personal rating has sunk to among the worst for any British leader and his party trails the populist Reform UK party ⁠in opinion polls, suggesting Labour would lose a national parliamentary election due in ⁠2029.

Nevertheless, some senior cabinet ministers publicly backed Starmer on Friday. Calls ​for his resignation, which grew last month following new revelations about the hiring of Peter Mandelson as U.S. ambassador, still mostly come from the fringes of the Labour Party and opposition political parties.

WHY HASN'T SOMEONE CHALLENGED STARMER? Timing is everything, and right now Labour is facing acute problems, both domestically and ​internationally, that a replacement ‌leader would inherit without any obvious new solutions available to them. These include tight fiscal constraints, rising living costs and demands for more defence spending, set against a backdrop of heightened global uncertainty and nervy financial markets that could react badly to any sign of political instability.

In addition, of the three candidates seen as most likely replacements for Starmer, two have good reason to wait. Greater Manchester Mayor Andy Burnham doesn't have the seat ​in parliament he needs to mount a challenge, and former deputy prime minister Angela Rayner has yet to fully resolve the tax issues that prompted ‌her resignation from office last year.

The third, Wes Streeting, is currently health minister.

HOW COULD A RIVAL CHALLENGE FOR STARMER'S JOB?

A leadership challenge can be triggered if there is enough support from within Labour ‌for a candidate to replace Starmer.

It is generally harder for Labour lawmakers to remove a prime minister than the rival Conservative Party, which went through five prime ministers in eight years from 2016, because the Labour rebels would have to rally behind specific candidates, rather than just declare 'no confidence' ​in the leader.

Labour members of parliament have never successfully removed a sitting prime minister in the party's more than 125-year history.

HOW WOULD ANY FUTURE CONTEST WORK? Any candidate wishing to ‌make a challenge would need to secure the public support of 20% of Labour members of parliament. With Labour currently holding 403 seats, that equates to 81 backers.

Candidates also must meet thresholds for support from grassroots Labour Party organisations, and from affiliated organisations such as trade unions.

Starmer would have an ⁠automatic right to ⁠be on the ballot paper, if he chose to fight the contest.

If only one candidate qualifies, ‌there is no vote: the candidate is elected unopposed as Labour leader and becomes prime minister.

If more than one candidate qualifies, the winner is decided by a ballot of Labour ​members and affiliates. The winner then becomes ​prime minister.

WHAT OTHER OPTIONS ARE THERE?

Some Labour lawmakers have suggested Starmer should set out a timetable for ‌his departure, allowing for a managed transition to a new leader who would contest the 2029 election.

Starmer has said he intends to lead the party into the next election. In 2006, former Labour Prime Minister Tony Blair set a deadline for his departure after some junior members of his government resigned, but he did not quit immediately. (Reporting by William James; Editing by Toby Chopra)