ES News email The latest headlines in your inbox twice a day Monday - Friday plus breaking news updates Enter your email address Continue Please enter an email address Email address is invalid Fill out this field Email address is invalid You already have an account. Please log in Register with your social account or click here to log in I would like to receive lunchtime headlines Monday - Friday plus breaking news alerts, by email Update newsletter preferences

A bruising battle over the leadership contest rules deepened today as Angela Eagle’s supporters insisted Jeremy Corbyn must have the backing of at least 50 MPs or MEPs to defend his crown.

They spoke out after Christine Shawcroft, a Corbyn ally who sits on Labour’s ruling NEC, insisted the party’s rulebook meant only challengers needed to pass the threshhold, not a sitting leader.

“I think most of us are quite clear what the rules are saying,” she claimed.

“The only reason we are having this argument is that Jeremy Corbyn’s opponents want to keep him off the ballot paper because that’s their only hope of winning. When he’s on that ballot paper he will win.”

The NEC is due to meet tomorrow to vote on how to interpret the rules.

Labour Party general secretary Iain McNicol is understood to have received legal opinion saying that Mr Corbyn needs the 50 names, but the leader has one saying the opposite.

Former acting leader Harriet Harman said Mr Corbyn had “no right to fail” and having lost the support of MPs should be ruled out of the running.

“If you fail, you can’t take the party down with you,” she said. “That’s not fair.”

She denounced threats of legal action by Mr Corbyn if the NEC rules against him. “The idea that the leader of the party, having lost the confidence of Labour MPs, then takes the national executive of the party to court is just more dysfunction upon more dysfunction and the party is suffering.”

Under party rules any challenger must have nominations from a fifth of the parliamentary party to be allowed to stand. But the situation is less clear for the incumbent.

A senior party source said it was not a case of keeping anyone off the ballot paper, but that all had to follow the same rules. He added: “Why does Jeremy want special treatment?”