Voting has closed in local elections, a moment of potential peril for Rishi Sunak, with the Conservatives braced for heavy losses that could destabilise his premiership. The elections, in more than 2,600 seats across 107 English councils, are seen as a key test of whether the Conservative party is as unpopular with voters as the polls suggest. They also represent the prime minister’s final chance to stem speculation of a Labour landslide at the general election – and to quash any potential rebellion from Tory plotters keen to oust him before it. His first big test will be the parliamentary byelection in Blackpool South, where the former Tory MP Scott Benton resigned after being found guilty of breaching standards rules in a lobbying scandal. Labour said it was hopeful of taking back the seat, which Benton won with a majority of 3,690 in 2019, but the race for second place could be problematic for Sunak if the Tories are outflanked on the right by the Reform party. There are also concerns in No 10 that Sunak may face a leadership challenge if the Tories lose the West Midlands and Tees Valley mayoralties. Their candidates – Andy Street and Ben Houchen – are high-profile locally and have distanced themselves from the party. Polling before voting opened suggested the West Midlands contest was on a knife-edge, with YouGov putting the Labour candidate, Richard Parker, two points behind Street. Houchen was seven points ahead of his Labour rival, Chris McEwan, in Tees Valley, but was expected to win as he started from a high bar, taking 73% of the vote last time. If either of them lose, some Tory insiders fear Sunak could face a confidence vote – just 52 Tory MPs need to feel despondent enough about the state of their party to trigger one. The experiences of Theresa May and Boris Johnson with such votes suggests that even prime ministers who win them can still see their authority drain away. Ten metro mayoralties including London are being contested, as are 37 police and crime commissioner roles in England and Wales. There are no elections in Scotland or Northern Ireland, and no local council elections in Wales. Labour will be keeping a close eye on the contest for North of Tyne mayor, where the polls suggest that incumbent Jamie Driscoll – who was barred from running as the party’s candidate amid accusations of factionalism – could run Labour candidate Kim McGuinness close. The Tories could face an upset in a newly created mayoralty, York and North Yorkshire, in Sunak’s own back yard, which had been assumed to be a safe Tory seat but now looks in play for Labour. Sadiq Khan, the mayor of London, is expected to win a record third term in the capital after a bitterly fought contest with his Tory rival, Susan Hall, who has faced criticism for pushing the party to the right. Some psephologists have predicted the Conservatives could lose 500 council seats – about half of those the party is defending this time around – but Labour sources have said the figure is too ambitious. This set of local council seats was last contested in May 2021, when the Conservatives under Johnson were at a high point after the UK’s Covid vaccine rollout, and the party enjoyed its strongest performance since 2008. Sunak has faced months of often frenzied conjecture over his leadership but before polling day his aides said he was feeling more secure. During the last two weeks he has made a series of policy announcements aimed at securing his base – welfare reform, the Rwanda deportation plan and defence spending increases – with more expected in the days ahead. The Commons leader, Penny Mordaunt, who is seen as a future leadership contender, responded to speculation about her ambitions on Thursday by saying: “It’s not going to be Pimm’s with Penny, I’m more of a pints with Penny person”. She added: “I too have read that I’m to be installed rather like a new boiler into No 10 next week … But let me say again, I support our prime minister and I will continue to support him after this weekend and beyond.” The results for all the contests will be declared from the early hours of Friday through to Saturday afternoon, when the West Midlands result is declared.