The leader of Britain's opposition Labour Party leader has urged a lawmaker challenging him for the job to "think for a moment" about her decision.

Angela Eagle, the party's spokeswoman on business issues, will launch her challenge to Jeremy Corbyn on Monday amid party turmoil following voters' decision to leave the European Union.

Corbyn told the BBC on Sunday that this is the moment to offer a differing vision to the Conservatives and austerity programs. The Tories are holding a contest of their own to replace outgoing Prime Minister David Cameron, who is resigning after losing the vote.

Corbyn is in jeopardy over fears that he wouldn't be able to rally national backing to win a new election should Cameron's successor choose to call one.