Britain's opposition leader Jeremy Corbyn will face a leadership contest unless he considers his position, Labour Party MP Angela Eagle says, saying she has the necessary support to trigger a challenge and is ready to do so.
Mr Corbyn has refused to resign following Britain's vote to leave the European Union, despite mass defections from his policy team and a no confidence motion that was passed by an overwhelming majority of MPs in his own party.
Discontent with the veteran socialist has been simmering for months among Labour members of parliament, but the crisis has come to a head since the Brexit vote, which has turned domestic politics on its head and raised the possibility of an early general election.
Critics accused Mr Corbyn of leading a half-hearted campaign in favour of staying in the EU.
"I have the support to run and resolve this impasse and I will do so if Jeremy doesn't take action soon," said Ms Eagle, who stood down as the party's spokeswoman on business issues after the EU vote and is the leading contender to launch a challenge.
In response, Mr Corbyn urged the party to reunite and restated his determination to carry on as leader.
"When we do things together, we are very strong. Now is the time to come together," he said in a video message posted on Twitter.
Mr Corbyn says he retains the support of the party's grassroots members, who elect the leader, and that resigning would be a betrayal of those who overwhelmingly voted him into the job last September.
The outcome of the tussle for control of Labour, between Mr Corbyn's left-wing supporters and more centrist elements, will define the party's voice in the negotiations that will shape future ties between Britain and the EU.
To trigger a leadership election, a rival candidate needs the support of 51 or more elected MPs.
Mr Corbyn has said he will stand again in any contest to replace him.