Jeremy Corbyn does not need MPs' support to fight a fresh leadership election, according to party legal advice obtained by HuffPost UK.
As the Labour leader was rocked by multiple resignations from his Shadow Cabinet, allies said that any 'coup' attempt would fail because the party rules mean he will not require MP nominations to fight on.
Corbyn was elected by a landslide in the last leadership election in 2015 and has seen a wave of online support from members over the weekend.
Some of the plotters hoped that he would lack the numbers of MPs to fight off any new leadership race.
But the legal advice from Doughty Chambers lawyers, shows that the need to have 20% of MPs or MEPs' nominations only applies to challengers, not to the 'incumbent'.
The legal advice, in a lengthy document passed to HuffPost UK, is being used by Corbyn's team to warn MPs that they cannot oust the sitting leader without a vote by the party rank and file outside Parliament.
Supporters of the leader believe he will win an even bigger mandate in any fresh election and claim that party members are furious with MPs for the coup attempt at a time when the Tories are split over the Brexit vote in the EU referendum.
A further key piece of the advice states "the incumbent does not require to be nominated in order to appear on the ballot paper".
Critics of Corbyn have two rival legal opinions, suggesting that because the current rules are 'silent' on the explict need for nominations, he would indeed need nominations from MPs.
The conflicting legal opinions could see the party's general secertary Iain McNicol side with the MPs rather that the leader, but the issue may be settled in the courts.
Critics of the leadership say that the precedent on 1988 proved that Neil Kinnock needed nominations when challenged for the top job by Tony Benn.
The party's ruling NEC, where Corbyn has a narrow majority, may however decide that the current advice is sufficient to allow Corbyn an unhindered fresh shot at getting on the ballot.
The #KeepCorbyn hashtag was used by his supporters this weekend as fears of the MPs' plot were realised.
A 38 Degrees petition of 'confidence' in the Labour leader attracted 187,000 signatures within a matter of hours.
MPs still loyal to Corbyn came out in his support, from Shadow Chancellor John McDonnell to Diane Abbott and Jon Trickett.
McDonnell vowed that he would 'never' run for the leadership himself and would act as campaign manager for Corbyn in any new contest.
Shadow minister Rebecca Long Bailey also tweeted her backing.
Leading trade unions ralled to his support on Friday night and today NEC member Jamie Bramwell issued a statement attacking the MPs plotting to unseat Corbyn.
"I am appalled and disgusted at the behaviour of those MPs in OUR party who wish to undermine OUR leader, Jeremy won the leadership contest with an overwhelming majority and some MPs need to respect the membership of OUR party," he said.