A “Daily Mirror” poll puts Mr. Corbyn ahead of Prime Minister Theresa May for the first time.

British Opposition leader Jeremy Corbyn has vowed to “try to force an early general election” after Prime Minster Theresa May lost her parliamentary majority, in an interview published on Saturday. Mr. Corbyn’s Labour Party outperformed expectations in the June 8, 2017 election, turning what was predicted to be a procession for Ms. May into a disaster, severely weakening her authority as Britain kicks off crucial Brexit talks.

Mr. Corbyn told the left-wing newspaper the Daily Mirror that it was “ludicrous” to believe the Conservatives’ minority government could survive, and that his party “will challenge this government at every step and try to force an early general election”. A poll for the paper asking the public who would make the best Prime Minister has put Mr. Corbyn ahead for the first time, although other surveys have revealed little appetite for another vote after two tumultuous years for British voters.

Ms. May’s party is currently in negotiations with Northern Ireland’s DUP to secure an informal parliamentary deal that would give it an effective majority. MPs will vote on Ms. May’s legislative agenda next week, and opposition parties have vowed to block her programme in what is traditionally seen as a test of confidence in the government.

Members of Ms. May’s own party are reportedly lined up to dump their leader if it looks like her government will lose the vote.