Labour MPs prepare to DEFECT if Andy Burnham fails to oust Keir Starmer from No10

These conversations have been put on hold pending the outcome of the crucial vote on June 18, which Mr Burnham hopes will provide his springboard to challenge Sir Keir Starmer for the premiership.

MPs on the party's left flank believe a victory for the Greater Manchester Mayor would steer Labour towards policies more aligned with their political outlook.

Current polling suggests Labour holds a slender three percentage point advantage over Reform in the constituency, with right-wing support fragmented between Nigel Farage's party, the Conservatives and Rupert Lowe's Restore Britain.

Two former ministers have predicted Sir Keir will be forced from Downing Street regardless of what happens in Makerfield.

Jess Phillips, who stepped down as safeguarding minister this month, declared at the Hay Festival on Monday: "I think even if Andy Burnham doesn't win in Makerfield there will be a change of the Prime Minister."

She added: "I've never been to Wigan in my life, so I have absolutely no idea about the people there, so I shall go and find out. But, yes, I imagine Andy Burnham will win it, and I imagine then that the Prime Minister changes."

Alex Davies-Jones, who resigned as justice minister following what she described as catastrophic local election results, told the Mail that "things cannot continue with Keir as leader".

She stated: "He does not have the support of the country or the parliamentary party."

Ms Phillips used her resignation letter to accuse Sir Keir of lacking the "fight and drive" to deliver meaningful change.

Green Party sources have identified Norwich South MP Clive Lewis and Leeds East MP Richard Burgon as among those prepared to cross the floor to join Zack Polanski's party, reports The Telegraph.

Both Mr Lewis and Mr Burgeon saw their local parties suffer significant losses in the May 7 council elections, with the Greens seizing control of Norwich city council from Labour while the party also lost its grip on Leeds council.

In a veiled swipe at Reform UK, a Green Party source said: "We are more interested in winning elections than defections.

"However, we know that more and more Labour voters and politicians recognise the Green Party as the most authentic party of the Left...we will always talk with anyone who shares our values."

Labour shed nearly 1,500 councillors across England in the local elections, with the Greens capitalising on the party's struggles by capturing the Gorton and Denton constituency from Labour in February.

Meanwhile, left-wing Labour MPs are growing increasingly frustrated with Mr Burnham's shifting positions on key issues and are contemplating fielding their own candidate against him in any future leadership contest.

According to The Times, MPs on the party's left flank are unhappy with the Greater Manchester Mayor's support for Shabana Mahmood's proposed immigration reforms and his backing of Government guidance on single-sex spaces.

One left-wing MP told the newspaper: "A lot of us are increasingly frustrated that he's being portrayed as the saviour of the left when he's nothing of the sort. There have been discussions about whether we put up a candidate to try to force him into more progressive positions."

A Labour source suggested that introducing another left-wing candidate could "concentrate minds" among MPs, though warned that forcing Mr Burnham to spend weeks discussing Gaza would leave him weakened.

Diane Abbott, the suspended Labour veteran, and former Shadow Home Secretary responded to reports of Mr Burnham's immigration stance by saying: "Meet the new boss, same as the old boss."