LONDON: Angela Eagle is preparing to fight Jeremy Corbyn for the Labour leadership after he defied MPs, MEPs and even his own deputy leader by refusing to stand down.
Tom Watson last night ruled himself out of standing and blamed the shadow chancellor John McDonnell for persuading Mr Corbyn to stay in what he called a "great tragedy".
The Labour leader's defiance came on another day of resignations and after Gordon Brown, Ed Miliband and David Cameron all called on him to go in the national interest.
Fifty MP signatures backing Ms Eagle, the former shadow business secretary, are now expected to be submitted within 24 hours, triggering a bruising leadership contest that could last for months.
Labour sources described it as a battle for the "survival of the party" as former Blairites and Brownites unite around Ms Eagle while leading trade unions and hard-Left activists back Mr Corbyn.
Last night, the leaders of 10 trade unions including Unite, GMB and Unison condemned the coup as "deeply regrettable and unnecessary" but indicated they would not stand in the way of a formal leadership contest.
Mr McDonnell described rebellious MPs who confronted Mr Corbyn at a meeting on Monday night as acting "like a lynch mob without a rope" and said the Labour leader would not be "bullied" into quitting.
Moderates are preparing to mobilise the party's pro-EU campaign structure and use its data to help thousands of activists target Labour members who backed Remain to defeat Mr Corbyn.
However, the Labour leader's office is confident they can see off the challenge by recruiting 100,000 pounds 3 temporary members, gaining funding from the unions and deploying supporters from Momentum, the pro-Corbyn activist group.
Last night, Mr Corbyn was cheered by Left-wing activists at a speech in central London where he declared he would carry on. However, his speech was disrupted by hecklers who shouted: "What about Europe? Where were you when we needed you?"
Tension from days of infighting has resulted in death threats with Labour MPs going to the police over abusive messages and telephone calls linked to their failure to back Mr Corbyn.
Speaking to the BBC, Mr Watson brought an end to backroom negotiations about whether he or Ms Eagle would stand for the leadership.
"I won't run. When I ran for deputy leader I did say to our party members and our trade unions that I believe that my role is trying to bring the party together," Mr Watson said. He apologised to the country for the "mess" at Westminster and said he had called on Mr Corbyn to resign during a second face-to-face meeting about his future.
"I went to see Jeremy today to see whether we could sort of find a way to get a negotiated settlement but he was unwilling to move from the position he's in so we're still in an impasse, I'm afraid," he said.
"It's a great tragedy. He does have a members' mandate but those members who join a political party know that you also need a parliamentary mandate if you're to form a government."
Mr Watson also named Mr McDonnell - the shadow chancellor and one of Mr Corbyn's closest allies - as the man persuading him not to quit despite almost 80 per cent of his MPs backing a no confidence motion. Mr Corbyn's office played down that claim.
Another day of infighting began with some of Labour's most well-known figures calling on Mr Corbyn to go in the interest of the party he leads.
Tessa Jowell, the former culture secretary, looked into the camera during an appearance on ITV's Good Morning Britain and issued a direct plea for his resignation. "Jeremy, you love the Labour Party like I do and the Labour Party has given you every opportunity that you have been able to exercise to make life for your constituents better," she said.
Dame Margaret Beckett, who was briefly acting Labour leader in the Nineties, appeared close to tears as she said that "the interests of those you lead come before your own".
Pat Glass, the Labour MP promoted to shadow education secretary, announced she was quitting after less than two days in the role, saying the situation was "untenable".
By lunchtime Mr Corbyn's two predecessors had gone public with their disquiet. Ed Miliband said he had "reluctantly reached the conclusion that his position is untenable" during an appearance on BBC Radio Four's World at One. He said: "I am not a plotter, I am somebody who cares deeply about my country, deeply about my party, deeply about the causes that Jeremy and I care about.
"I think the best thing on all of those criteria is that he stands down, painful though that might be for him and many of his supporters."
Gordon Brown, Labour's last prime minister, said: "I don't think Jeremy Corbyn is going to stay. I think he is going to go but I think the issue is how the Labour Party becomes electable."
A majority of Labour's MEPs also joined forces in a letter calling for Mr Corbyn to resign, while during Prime Minister's Questions, Mr Cameron criticised his role in the EU referendum campaign. He said: "It might be in my party's interest for him to sit there, it's not in the national interest and I would say, for heaven's sake man, go."
However in a piece for the New Statesman, Mr McDonnell wrote: "The truth is that Jeremy is not standing down. In the Labour Party our members are sovereign. There was an election held and a decision made, and 172 people cannot outweigh a quarter of a million others.
"It would risk sending the worst possible message we could send as a party to the electorate - that Labour does not respect the democratic process."