Is Starmer's leadership under serious threat?

The prime minister is facing the first explicit threat of a leadership challenge from one of his MPs, but how much of a threat does it pose to Sir Keir Starmer?

The former minister Catherine West's interview with Radio 4's PM programme immediately raised eyebrows around Westminster.

Plenty of Labour MPs from across the party have told us they didn't see it coming.

"What the hell is going on?" said one figure on the Left. "Crikey," said another.

Equally succinctly, a former frontbencher declared her intervention to be "bonkers".

But another told us they were aware of her plans from messages that had been shared between some Labour MPs.

They characterised her intervention as an expression of exasperation and frustration.

"It is a howl of pain," said one minister, reflecting that so many people in the Labour Party this weekend are hurting.

"Many have lost their social circle in their patch. Dear friends, who have worked incredibly hard as councillors, who have been thrown out and it's not their fault," one MP said.

Downing Street are trying to ignore West's challenge and the various leadership camps are denying that they had anything to do with it.

It may peter out.

But "it might just break the impasse," said another MP, by giving others a vehicle to express their view that the leadership needs to change.

For a challenge to get off the ground, 20% of Labour MPs, 81 people, have to back it.

West says she currently has 10 supporters and so is a long way short of that.

Some MPs have told us she has no chance of getting the MPs she would need.

An MP on the right of the party suggested that she might be inadvertently helpful to the PM.

If she can't get enough supporters Sir Keir could then declare that there was no appetite for a contest and move on.

But others - including an ally of the prime minister - think she might cross the threshold.

Within the party there is feverish private discussion about Sir Keir's future, with some anticipating a move from one of the challengers in the coming days.

As one veteran Labour figure put it: "Basically nobody beats Andy Burnham. So if you want anyone other than Andy you need this to happen sooner rather than later."

Others are desperate for their colleagues to calm down.

It would be "ego over country," said one MP from the 2024 intake. "It's self centred. If you want it to be better then get stuck in. We're in government, this isn't a game," they added.

Another, a veteran, said: "I take a day off and all hell kicks off. It's all a bit of a fiasco. People are disorientated, cheesed off and fed up. There is a general view that in time Keir will have to go, but we don't want blood on the walls. Let's give it time, and give it time for Andy Burnham to come back."