Two senior members of Britain's anti-European Union U.K. Independence Party said Sunday they will run to become its next leader, days after the previous front-runner quit the race and resigned from the troubled party.

UKIP, which played a key role in securing a June 23 vote to leave the EU, has been plunged into chaos since, with high-profile party leader Nigel Farage stepping down after the Brexit vote and his successor, Diane James, quitting after just 18 days.

On Monday the front-runner to take over, Steven Woolfe — who earlier this month was hospitalized following an "altercation" with a colleague — said he was withdrawing from the race and resigning from the party, describing it as "ungovernable."