Expectations among the governing Conservatives are low, but Sunak hopes his party will retain at least one mayoralty to help stem calls for him to quit before the parliamentary election, which he says will likely take place in the second half of 2024.
While governing parties often struggle in local polls, the expected Conservative losses in councils and a parliamentary by-election in the northern English town of Blackpool will boost opposition Labour's hopes for a sweeping victory at the national election.
"We are expecting to see significant losses," finance minister Jeremy Hunt told Sky News on Wednesday. "If you want better public services... and lower taxes, then you should vote Conservative tomorrow."
Labour leader Keir Starmer said his party needed to make gains in Thursday's elections, which cover more than 2600 council seats and 11 mayors across England as well as 37 police and crime commissioners in England and Wales.
"We have to show that people have the confidence and the trust to vote for this changed Labour Party," he said.
The local polls will offer the last glimpse of voting patterns before the UK national election, which opinion polls say the Conservatives are set to lose.
A YouGov/Times voting intention poll put the Conservatives on just 18 per cent - their lowest level since 2019 - against Labour's 44 per cent.
Labour looks set to overturn the Conservative majority in the parliamentary constituency of Blackpool South, but party officials do not expect to oust the high-profile Conservative mayor, Ben Houchen, in Tees Valley in northeast England.
Another mayoral contest in the West Midlands, where Conservative Andy Street has been in power since 2017, looks tight.
Sunak's team hopes that keeping Tees Valley and possibly the West Midlands, too, will stifle calls from some in his restive party for his resignation.
"We are rightly out campaigning for every vote," Sunak's press secretary told reporters on Wednesday, listing what she called his recent successes such as promising to raise defence spending and passing a law to send illegal asylum seekers to Rwanda.
She said Sunak had campaigned with both mayors when asked about Houchen and Street's attempts to distance themselves from the Conservatives, instead promoting their personal brand.
