Wallasey MP Angela Eagle, who resigned as shadow business secretary last week, said she will announce her plans to bid for the Labour leadership on Monday.
The leadership challenge is a bid to “heal the party” she said, criticizing current leader Jeremy Corbyn for failing “to lead an organized and effective” party.
Jeremy Corbyn urged her to “think again”.
The BBC reports:
Mr Corbyn, who was elected by Labour members but is now opposed by many of his own MPs, said he was “disappointed” but would fight the challenge.
Labour’s ruling National Executive Committee will decide whether he must seek MPs’ nominations to run again.
Mr Corbyn has faced dozens of resignations from his front bench in the weeks since the EU referendum.
He had been accused of failing to win over Labour voters to the Remain side and many of his MPs feel he would not lead the party to victory, should there be a snap general election following David Cameron’s decision to resign as prime minister.
After losing a no confidence motion among Labour MPs by 172 votes to 40, it is thought he may struggle to get the backing of 20% of Labour MEPs and MPs – 51 names – needed to get on the ballot paper in a leadership contest.
If the NEC – the governing body and administrative authority of the party – rules he has to get 51 nominations to defend his leadership and he fails to do so, his name would not go forward to a vote of the wider membership.
But Mr Corbyn told the BBC he was “expecting to be on the ballot paper because the rules of the party indicate that the existing leader, if, challenged, should be on the ballot paper anyway”.
Asked if he would go to court should the NEC rule against him, Mr Corbyn said: “I will challenge that, if that is the view they take.”
Union leader Len McCluskey has warned of “a lasting division” in the party if Mr Corbyn’s name does not appear.
Ms Eagle told the BBC’s Sunday Politics it was “not clear from the Labour Party rules”, but added: “Anyone who aspires to lead who cannot get 51 members… is not going to be able to do the job properly.”