Polling stations opened across England early Thursday for a host of crunch local elections likely to increase the pressure on embattled Conservative Prime Minister Rishi Sunak.
The polls - a mix of council, mayoral and other local contests as well as a parliamentary by-election - are the last major electoral test before a general election set for later this year.
Sunak's ruling Tories, in power nationally since 2010 and defending hundreds of seats secured the last time these local elections were held in 2021, are tipped to suffer heavy losses.
Polls over the last two years also consistently show the Conservatives on course for defeat in the upcoming general election.
Voting ends at 2100 GMT, with results for Thursday's contests, including in the by-election for parliament in Blackpool South, expected to begin emerging in the early hours of Friday.
But many councils will only annnounce winners later in the day while key regional and London mayor races will not report results until over the weekend.
The capital's Labour mayor Sadiq Khan is expected to win a record third term easily, but mayoral contests in the West Midlands and Tees Valley, in northeast England, are predicted to be tight.
A victory for the Labour opposition in either regions, home to bellwether constituencies, would be hailed as further evidence voters are ready to return the party to power nationally.
Speculation is rife in the UK parliament at Westminster that such a bad showing may lead some restive Tory lawmakers to try to replace Sunak, who has been in charge since October 2022.
But wins for the incumbent Tory mayors in the West Midlands and Tees Valley, Andy Street and Ben Houchen, would boost their hopes that the beleaguered leader can still revive their fortunes.
In line with other by-elections in recent years, Labour is expected to seize the Blackpool South parliamentary seat from the Tories after their MP resigned over a lobbying scandal.
Pollsters forecast that the Conservatives could lose about half of the nearly 1,000 council seats they are defending in cities, towns and districts across England.
In Wales - as well as England - voters will only elect police and crime commissioners, who control forces' budgets, set their priorities and have the power to hire and fire chief constables.
Again, political analysts say the Tories may lose up to half of their 29 commissioners, with 37 in total up for grabs. (AFP)
Karan Johar and Smriti Irani