As the nation awaited the results of local elections that would likely increase pressure on the party's beleaguered head, Rishi Sunak, the ruling Conservatives in Britain lost a parliamentary seat to the main opposition Labour party on Friday.

In the most recent by-election, Labour defeated the Conservatives in the northwest English constituency of Blackpool South, suggesting that a general election is imminent.

Voters in a variety of council, mayoral, and other local elections around England cast ballots on Thursday, prompting the vote that resulted from a lobbying scandal that led to the resignation of the area's Conservative MP.

With a 26.3 percent swing, Chris Webb of Labour won, marking the third-largest margin of victory for Labour over the Conservatives in a by-election since World War II.

“This seismic win in Blackpool South is the most important result today,” said Labour leader Keir Starmer, tipped to be Britain’s next prime minister.

The polls represent the last major ballot box test before Sunak goes to the country in a nationwide vote expected in the second half of the year.

His ruling Tories, in power nationally since 2010 and defending hundreds of seats secured the last time local elections were held in 2021, are tipped to suffer heavy losses.

Early results showed that Labour was making gains in council seats, but all eyes were on key regional and London mayor races, the outcome of which are only expected later Friday and Saturday.

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 of the regions, home to bellwether constituencies, would be hailed as further evidence voters are ready to return the party to power nationally.