Labour deputy leader Tom Watson has hit back at a bid to oust him by abolishing his post, calling it a "sectarian attack" on the party's "broad church".
Mr Watson told the BBC he only found out in a text message last night that a motion had been tabled by Jeremy Corbyn ally Jon Lansman, founder of Labour grassroots group Momentum.
Mr Corbyn's party has now been plunged into chaos ahead of its party conference in Brighton this weekend, with its ruling National Executive Committee (NEC) set to vote again today on whether to abolish the position of deputy leader.
Mr Watson said: "I was taken by surprise by it, because it wasn't on the agenda of the meeting, there were no papers tabled. There was no warning.
"I got a text message in a Chinese restaurant in Manchester to say that they were abolishing me."
"It's a straight sectarian attack on a broad church party," he said.
"And it's moving us into a different kind of institution where pluralism isn't tolerated. Where factional observance has to be adhered to completely.
"And it... completely goes against the sort of traditions that the Labour Party has had for 100 years."
Moves to oust him were labelled "mad" and "f***ing insane" by Labour MPs. Former leader Ed Miliband said those responsible had "taken leave of their senses".
The move to abolish the deputy leader post without warning or debate is undemocratic, wrong and should not happen. Those who came up with the idea for the eve of Labour Conference have taken leave of their senses.— Ed Miliband (@Ed_Miliband)September 20, 2019
The surprise attempt to get rid of the deputy post on Friday failed at an NEC meeting because it was ruled out of order.
Despite a 17-10 vote in favour of debating the motion, which was pushed by Corbyn ally Mr Lansman of the Momentum group, the necessary two-thirds majority to overturn a ruling of the chair was not met.
Mr Watson has publicly clashed with Mr Corbyn on a number of occasions and has been pushing for Labour to back staying in the European Union in any future referendum.
He recently called for a new Brexit referendum to be held before a general election.
Tom Watson says UK needs a second referendum to solve Brexit deadlock
The attempt to remove him provoked a furious response from Labour MPs at a time when the conference is meant to put Mr Corbyn's team firmly on an election footing.
Former Labour leader Mr Miliband said: "The move to abolish the deputy leader post without warning or debate is undemocratic, wrong and should not happen.
"Those who came up with the idea for the eve of Labour conference have taken leave of their senses."
Ex-minister Yvette Cooper tweeted: "This is completely mad and incredibly destructive. Country faces serious challenges & General Election could be imminent. @UKLabour conference shd be about country & about pulling together. Instead we get this."
This is completely mad and incredibly destructive. Country faces serious challenges & General Election could be imminent. @UKLabour conference shd be about country & about pulling together. Instead we get this. https://t.co/2aVwz6qH8X— Yvette Cooper (@YvetteCooperMP)September 20, 2019
Former Cabinet minister Ben Bradshaw said the attempt to "purge" Mr Watson was "totally f***ing insane".
Tottenham MP David Lammy said: "Tribal infighting in the middle of a Boris Johnson-inspired national emergency makes me want to weep.
"My constituents and millions of others across the country desperately need the Labour party united right now. The Tories, not Tom Watson, are our opponents. Let's fight them."
Tribal infighting in the middle of a Boris Johnshon-inspired national emergency makes me want to weep. My constituents and millions of others across the country desperately need the Labour party united right now. The Tories, not Tom Watson, are our opponents. Let's fight them.— David Lammy (@DavidLammy)September 20, 2019
Labour was already facing a battle over Brexit policy at the conference.
Activists have mounted a campaign to push the party to throw its weight behind the Remain cause in any second referendum despite Mr Corbyn's hints he could stay neutral in a public vote.
Mr Corbyn has said that a Labour government would secure a "sensible" Brexit deal and put that to a referendum, with the other option being to stay in the European Union.
Mr Corbyn rejected claims that his policy was a "muddle" and that he was failing to offer leadership on an issue of crucial national importance.
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"I am not sitting on the fence," he told ITV Yorkshire.
"I think leadership comes from listening. I think leadership comes from asking people to look at the realities of the situation.
"It is not a muddled position. It is a position that takes the issue seriously."
But scores of motions submitted by constituency parties at the conference in Brighton have called for the party to back staying in the European Union - which could mean campaigning against a deal secured by Labour negotiators.
Scottish and Welsh Labour are both committed to the Remain cause and members in Northern Ireland have submitted a motion to conference warning that "any form of Brexit threatens jobs, workers' rights, migrants, the NHS, public services and the environment".
Brighton Kemptown MP Lloyd Russell Moyle said: "As an English Labour MP, I worry about the message it sends to voters in the rest of the UK to have UK Labour contradicting the position they hear from their own Labour parties."
More than 90 motions are thought to have been submitted on Brexit, the majority supporting a Remain stance.
Efforts to find an agreed form of words for a conference motion will take place at a behind-closed-doors meeting, with a vote on the party's position expected on Monday.