New Delhi, May 8 -- British voters cast ballots Thursday in local and regional elections that could shake up the country's politics and deliver a heavy blow to embattled Prime Minister Keir Starmer.

Starmer's center-left Labour Party is bracing for big losses in polls that will choose about 5,000 local councilors and a handful of mayors across England, as well as semiautonomous parliaments in Scotland and Wales. They are the biggest set of elections since Labour swept to power in a landslide in July 2024, and Starmer's opponents have painted them as a midterm referendum on the prime minister.

Polls closed at 10 p.m. (2100 GMT), and some local authorities will count ballots overnight, but the bulk of the results are likely to be declared...