Keir Starmer is fighting for his future. But there's a simple reason he might yet survive - Christopher Hope

The MP for Hartlepool continued: “It’s got to the point where I genuinely think that as far as the Prime Minister is concerned it’s not a case of if, it’s when.”

Then on Thursday, veteran Labour MP Graham Stringer spoke out saying: "I don't think the Prime Minister can survive for the rest of this parliament." Mr Stringer called for the PM to set out a timeline for his resignation.

Not even two years into this Labour government and the Prime Minister appears wracked by his inability to cut through to voters.

He has lost two chiefs of staff in Sue Gray and Morgan McSweeney, as well as three communications directors Matthew Doyle, Steph Driver and Tim Allan all falling by the wayside. These roles are still to be filled permanently.

Normally this type of back office problem would afflict a Prime Minister nearing the end of this time in office, not a PM so near to the beginning.

Yet despite these noises of the embattled Prime Minister is going nowhere. His press secretary said this week. "He is one of four Labour leaders to win elections; he has a clear five-year mandate. We are tackling the cost-of-living crisis, cutting waiting lists, and restoring pride in local communities."

It will take the resignation of a senior cabinet minister to trigger a full-scale crisis for Sir Keir, which looks some time off.

The experience of Scottish Labour leader Anas Sarwar is cautionary. He went out on a limb when he said in February that “the leadership in Number 10 must change”. Yet no Cabinet ministers followed him, and the moment went away.

But that moment looks set to come, unless the PM can arrest his sliding popularity. It may come after the local elections in May, if they are as catastrophic for Labour and the main parties as pollsters expect.

But it may not come and that is because there is no obvious candidate to replace him. Health Secretary Wes Streeting is tainted by his close links to Peter Mandelson; former Deputy Prime Minister Angela Rayner is still dealing with an ongoing tax probe; and Home Secretary Shabana Mahmood would not be accepted by the Parliamentary Labour Party uneasy about her stance on immigration.

The only other clear candidate Greater Manchester Mayor, Andy Burnham is not currently a sitting MP.

I have been told that Andy Burnham said to Angela Rayner he wants to be Prime Minister when they met recently. Burnham's team told me this was "simply rubbish and just untrue". Rayner's team said they "wouldn't get into private conversations".

Make of that what you will. But timing is everything, and the sense is that Starmer's rivals are waiting for the right time to act against his premiership. That moment seems certain to come , talking to Labour MPs this week, but it is likely to be months not weeks away.