(Bloomberg) -- Britons head to the polls on Thursday in a set of local elections that could put Prime Minister Rishi Sunak in a perilous position if the governing Conservatives suffer significant losses.

Thousands of politicians are vying for more than 2,500 council seats, 25 places in the London Assembly and 10 regional mayoralties, with voters able to cast their ballots between 7 a.m. and 10 p.m. Results are expected to start coming in early Friday, with the count in some areas continuing through to Sunday. 

The Tories have trailed Keir Starmer’s opposition Labour Party badly in national polling for months, and Conservative Peer Robert Hayward — a local elections expert — predicts they could lose more than 400 of the 900 council seats they’re defending. But party morale, and whether Sunak’s internal detractors move to oust him, may rest on the fate of just two candidates: the mayors of Tees Valley and the West Midlands, Ben Houchen and Andy Street.

The Tories — who shed more than 1,000 seats in last year’s local votes — are hampered this time around by their good performance in 2021, the last time the seats up for grabs on Thursday were contested. Then, the party benefited from a bounce after the roll-out of the Covid-19 vaccine, gaining more than 200 council seats and winning control of 13 councils.

About a third of councils are expected to declare results in the early hours of Friday, according to a tally by the Press Association. 

The most noteworthy result expected during the night is the count in the Parliamentary by-election in Blackpool South, triggered by the departure of Scott Benton. The former Tory MP quit the seat after being censured by Parliament’s standards committee for breaking rules governing lawmakers’ conduct.

The Tories have lost a string of by-elections on large swings to Labour and the Liberal Democrats in recent years and are defending a relatively small majority of fewer than 4,000 votes over Labour in Blackpool South.

Labour is seeking to make gains in key battlegrounds across the Midlands and North of England — that may serve also as a harbinger of what’s to come in a general election that Sunak must hold within 9 months. They’re also defending the mayoralties in London — where Sadiq Khan is aiming for a record third term, and Greater Manchester, where Andy Burnham is also seeking a third term. 

Tees Valley is due to announce its result — and therefore Houchen’s fate — on Friday afternoon, but Sunak will have to wait another day to see if Street has clung on in the West Midlands. The Greater Manchester result is also due on Saturday afternoon, while London’s City Hall doesn’t expect to announce the final result of the mayoral vote until late on Saturday or even early Sunday.

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