BRIGHTON, England — Jeremy Corbyn, Britain’s left-wing opposition leader, on Monday survived a serious challenge to his noncommittal approach to Brexit, winning a critical vote despite deep divisions at what most analysts expect to be the Labour Party’s last conference before a general election.

Demands for Labour to campaign more openly against Brexit were ultimately defeated on Monday afternoon, amid noisy protests from party activists, and after two days of intrigue and infighting at the conference, including an abortive coup against the party’s centrist deputy leader, Tom Watson.

After more than two hours of passionate debate on Monday, delegates finally drew back from inflicting defeat on Mr. Corbyn, a lifelong critic of the European Union who plans to face a general election with an ambiguous position intended to appeal to both those who want to stay in the bloc and to those who voted to leave it in a 2016 referendum.

Monday’s decision endorses a policy under which, if Labour wins an election, the party would negotiate a new Brexit deal and put it to a second referendum with the alternative being to remain in the European Union. But Mr. Corbyn will not commit himself to campaigning one way or the other.