A Labour rebel has compared Keir Starmer to a 'cockroach' saying she would not 'bet against' the PM surviving.
Jess Phillips, who quit last week backing Wes Streeting for the top job, grudgingly acknowledged Sir Keir's resilience when his 'back is against the wall'.
She also suggested the premier's allies had been deliberately trying to 'manifest a crisis' to help him cling on.
The comments came with a 'shadow' leadership contest in full swing. Greater Manchester Mayor Andy Burnham is fighting a by-election in Makerfield, with many assuming he will challenge if he succeeds in returning to the Commons.
However, Sir Keir has voiced defiance pledging to battle for votes from activists if there is an attempt to oust him.
The Government has been unveiling a blizzard of policies as the premier tries to show he still has a grip on the levers of power.
Jess Phillips, who quit last week backing Wes Streeting for the top job, grudgingly acknowledged Sir Keir's resilience when his 'back is against the wall'
That is despite signs that Cabinet ministers are already jostling for roles in a future Burnham administration.
Speaking on ITV's Peston programme last night, Ms Phillips was asked whether Sir Keir could end up clinging on.
'Don't bet against somebody who seems to have the resilience of... I was about to say a cockroach in a nuclear war, but it's about the PM and not what I would want to say at all,' she said.
'But it's absolutely right that when his back is against the wall he grows in stature and his team around him leap into action.'
Pressed on whether it was sustainable for the Government to be combating a crisis every week, Ms Phillips said: 'That's the problem, you can't manifest a crisis - although actually there's definitely been some effort to do that - every week so that you can rally the troops again back to your flag.
'But look, a minute seems like a long time in politics at the moment so who knows what is going to happen.'
Resigning as safeguarding minister last week, Ms Phillips said she believed Sir Keir was a 'good man' but that is 'not enough'.
'I think you are a good man fundamentally, who cares about the right things however I have seen first-hand how that is not enough,' she wrote in her letter to the PM.
'The desire not to have an argument means we rarely make an argument, leaving opportunities for progress stalled and delayed.'
Sir Keir has voiced defiance pledging to battle for votes from activists if there is an attempt to oust him