(Bloomberg) — Keir Starmer’s main leadership rivals went into Thursday’s local elections weighing a challenge against the prime minister. But Friday’s results showed some of them on increasingly shaky ground in their own constituencies, a factor complicating any potential coup.

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For the first time in 47 years Labour lost control of Tameside, the local authority in former Deputy Prime Minister Angela Rayner’s constituency, after Reform gained 18 of 19 seats.

Greater Manchester, where leadership hopeful Andy Burnham is mayor, lost swathes of council seats to both Reform and the Greens, turning the city Labour considers a stronghold into a patchwork.

The results expose the challenge for those with designs on replacing Starmer when, after a day of dismal local election results for Labour, even their own territory looks under risk of deluge from the populist wave.

A challenge would already have been “tricky,” said Luke Tryl, executive director of More in Common UK, and “in an already marginal seat things look even trickier.”

A poor result in these elections has long been seen as a critical test of Starmer’s ability to retain the confidence of his party. Allies of Rayner and Health Secretary Wes Streeting told Bloomberg before the election results that they were prepared to launch a bid to challenge Starmer, depending on the outcome.

Streeting had seemed on dicey ground after Labour’s landslide 2024 general election win, when his majority was slashed to little more than 500 votes against an independent candidate campaigning against the UK’s approach to Israel’s bombardment of Gaza.

It’s something MPs who don’t favor Streeting to replace Starmer point to as a risk of choosing a leader who is likely to lose his seat at the next general election, due in 2029. Still, in Redbridge, Streeting’s backyard, Labour lost 11 seats but remained the largest party by a hefty margin.

A sitting prime minister has never lost their own parliamentary seat, although Labour’s wipeout saw the Welsh First Minister Eluned Morgan lose hers on Friday.

It was clear, in their statements to the press, that many Labour members of parliament held Starmer responsible for Thursday’s poor results. The premier said he had no plans to step aside as Labour leader, even after a report in The Times newspaper that former leader Ed Miliband privately urged him to set out a time line for his resignation to avoid an unruly civil war.

Burnham, who currently lacks the necessary seat in Parliament to seek the premier’s job, is the preferred candidate for Miliband and many other left-leaning members of parliament who want the mayor to secure a seat in a by-election before moving against the premier.

Manchester’s losses included 20 of its contested seats on Wigan borough council, which spans the constituency Burnham held until 2017, before he left Westminster to stand for election as mayor. Reform gained 24 of 25 possible seats. Labour only retained control of the council because many of the ones it holds which weren’t up for election this year.

Labour holds most of the parliamentary seats in the area. Burnham was re-elected for a third term as mayor in 2024 with an overwhelming 63.4% of the vote share. Neither the mayoralty or those MPs’ seats were on the ballot this year, which in Greater Manchester was confined to certain local councils.

Although losses in Greater Manchester indicate Burnham may find it tricky to find a parliamentary seat he’s guaranteed to win, some pollsters believe his strong personal brand would buck the national trend.

Burnham’s approval ratings are far higher than that of Starmer’s, as well as those of the broader Labour Party’s, Tryl said. “Anyone who has done focus groups in region will tell you Burnham has something special,” he added.

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