Five Labour MPs have spoken to the Greens about defecting, the hard Left party's leader Zack Polanski has claimed.
Mr Polanski said he was speaking with a 'handful' of Keir Starmer's disaffected backbenchers in the wake of the Greens' shock win in the Gorton and Denton by-election.
Amid talk of plots to remove Sir Keir as Labour leader he said many party MPs were 'just hanging on in there' and waiting for a challenge to take place.
If five MPs were to defect it would make the Greens a larger party in the Commons than Reform, which has eight MPs.
It came as a leading expert said a hard-Left election pact between Polanski, Jeremy Corbyn and George Galloway could inflict 'very substantial' losses on Labour in May.
Sir Keir will hold a rare 'political' meeting of the Cabinet this morning to discuss the fallout from the disastrous by-election - and what it means for the local elections when Labour is already braced for heavy losses.
Mr Polanski, a London Assembly member, made the remarks in an interview in which he confirmed he will stand for a Westminster seat in the capital at the next general election - potentially in Diane Abbott's seat if she chooses to retire.
In a separate appearance in a political podcast MrPolanski, who has advocated the UK leaving Nato, scrapping its nuclear weapons and kicking US forces out of Britain, said he would work to build a 'relationship' with Vladimir Putin.
MrPolanski said he was speaking with a 'handful' of Keir Starmer's disaffected backbenchers in the wake of the Gorton and Denton by-election win (pictured with new MP Hannah Spencer)
It came as a leading expert said a hard-Left election pact between Polanski, Jeremy Corbyn and George Galloway could inflict 'very substantial' losses on Labour in May
In a separate appearance in a political podcast MrPolanski, who has advocated the UK leaving Nato and kicking US forces out of Britain, said he would work to build a 'relationship' with Vladimir Putin.
He told Matt Forde's Political Party podcast it was worth it even though he does not trust the Russian autocrat 'for a second'.
Speaking to the House magazine about Labour MPs he said: 'So many of them are so deeply frustrated and disappointed right now. In fact, I know they are because I speak to them.
'I know many of them are just hanging on in there, and I get that - they're waiting for another leadership contest.'
He added: 'If you speak to some Labour MPs, some days it seems like it's going to be their last day in the party, and other days they've seen a glimmer of light and think everything's going to be OK.'
He also said he regretted critisising Jeremy Corbyn when he was mired in an anti-Semitism scandal.
At the time he tweeted that being a 'pro-European Jew' were 'two reasons I couldn't vote for Labour under Jeremy Corbyn'.
He told the House he had since read a book which led him to believe there had been a 'cynical and systemic deliberate obfuscation of a really serious issue like anti-Semitism'.
And the former Lib Dem, who was born David Paulden before changing his name, added: 'I think there's a lot of inauthenticity in politics, but it's not coming from me.'
This month's by-election in Manchester saw Labour pushed into third place behind the Greens and Reform in what had been one of Labour's safest seats.
The victory came after Mr Corbyn's Your Party and Mr Galloway's Workers Party of Britain agreed to stand aside to avoid splitting the hard-Left and Muslim vote.
Elections expert Robert Hayward said there was 'potential' for the experiment to be repeated on a national scale in May in what will be the biggest test of public opinion since the general election in 2024.
At a press briefing on Monday, Lord Hayward said the effect could be particularly striking in London and other big cities where Labour is defending hundreds of seats from a challenge on the Left, as well as facing Reform and the Conservatives.
'In Gorton we saw the Greens, the Workers Party and Your Party work together successfully and there is potential now for them to do that again in a whole load of other places, including London,' he said.
'If they work together and if the Greens are able to maintain their current poll ratings, then the potential threat for Labour is very substantial indeed.'