If you want to be Prime Minister then there is a quality that stands out above all others – courage. And this morning one member of Keir Starmer’s benighted Government is finally displaying it. Wes Streeting.

Yes, the announcement he is finally rising above the parapet and putting himself forward to replace Keir Starmer is attended by a degree of Westminster sophistry. It was communicated via ‘friends’. It contains the modest fig leaf that he will not directly challenge the Prime Minister unless things ‘fall apart’.

But they are falling apart. They’ve been falling apart more or less from the moment Keir Starmer first crossed the threshold of Downing Street. They fell apart for 1,500 Labour councillors last Thursday. And they will fall apart for 70million Britons if Starmer is not swiftly removed from office.

The specific mechanism by which Sir Keir will be dragged out of No 10 is yet to be determined. But members of the Cabinet believe it will be triggered within the next 48 hours.

On Saturday, the Labour Party was stunned when the formerly unobtrusive ex-Foreign Office minister Catherine West announced she would directly challenge Starmer if ministers did not move against him by Monday.

Initially, this was seen as a freelance operation, unconnected to any of the major contenders. But her uncompromising and passionate demand for Starmer to go has seen her picking up support among her parliamentary colleagues.

There is currently uncertainty over whether West will secure the 81 nominations necessary to force a contest. But within the Cabinet there is now an assumption that once the Prime Minister has delivered his latest ‘reset speech’ tomorrow there will be a decisive push within the parliamentary party to force him to either announce his immediate departure, or set a timetable for a transition around the Labour Party conference.

‘We need to give him the opportunity to speak tomorrow,’ one Minister said, ‘but then, after that, people will move. I expect there will be well above the number needed to trigger a contest by this time on Tuesday.’

Some ministers have suggested Wes Streeting’s supporters may surreptitiously throw their weight behind West’s unconventional insurgency. But his allies expect the names to emerge via a different route, probably letters in which MPs state they no longer have confidence in Starmer.

The suggestion is these names will then be presented to the Prime Minister, who will be given the choice of either stepping down, or being dragged out of Downing Street.

One minister I spoke to suggested that Sir Keir will accept his fate. ‘I think he’ll go by the end of this week, without the need for a contest,’ they told me.

Yesterday it was clear Streeting’s boldness had caught his opponents within the party on the hop. ‘Oh s***!’ was the response of one Left-leaning MP when I informed him of a newspaper report that the Health Secretary was mobilising. But over the next 24 hours they will try to rally.

Aside from Starmer himself, the biggest potential loser is Andy Burnham. The Manchester Mayor was planning to announce later in the week that he had found a seat that would enable him to stage a triumphal return to Parliament.

But that plan has now been thrown into disarray, creating the prospect of him being left marooned in his North West citadel as events unfold 200 miles to the south.

With Burnham off the pitch, the Labour Left are currently scrambling to find a candidate of their own. Yesterday Angela Rayner put out a 1,000-word statement that criticised Keir Starmer for his ‘cronyism’, lambasted him for blocking Burnham from standing in the Gorton by-election and launched a slightly bizarre attack on Thames Water. But she pointedly held back from calling for Starmer to step down. Or announcing her own candidacy.

Some allies of Rayner claimed to me yesterday she was simply waiting to see if Streeting formally launched his bid, at which point she would enter the race to save Labour from a new Blairite usurper.

But another close friend told me she was losing the stomach for the fight. ‘The tax issue [unpaid stamp duty on her flat in Hove] comes up a lot on the doorsteps. People have concerns about her inner circle. And she knows it. There’s a feeling her moment has passed.’

Which leaves one other potential high-profile challenger. According to one minister, Environment Secretary Ed Miliband has been canvassing support from his parliamentary colleagues for his own dramatic return to the leadership. ‘Ed’s been canvassing a lot of people,’ the minister revealed. ‘He’s told friends his preference would be for Andy to stand. But if he can’t, then he’s prepared to step up himself,’

It’s now only three days since Keir Starmer reacted to his party’s local election defenestration at the hands of the voters with a tone deaf – some might say brain dead – response that he was going nowhere. But since that act of misplaced defiance his already precarious political position has imploded.

His terse Friday morning interview was followed on Saturday by the incomprehensible announcement he had selected Gordon Brown and Harriet Harman to help him drive through his ‘agenda for change’.

This was followed by an interview with a Sunday newspaper in which he declared he intended to serve two full terms, a prospect that was greeted with horror by his despairing parliamentarians.

As one Labour grandee observed: ‘Everyone’s been wondering who would finish off Keir Starmer. The reality is he’s finished himself off. His response to the local elections has been to say to the British people: “I know you say you don’t like me. Well, just wait and see. I’ll make you like me in the end.”’

A Cabinet minister agreed with this analysis. ‘With Morgan [McSweeney] gone, there is no one with the authority to tell Keir what to do, or rally the staff internally – let alone the Cabinet – behind a coherent strategy to save him.’

In the battle to replace Keir Starmer, Wes Streeting has stolen a march on his colleagues. And fortune usually favours the brave.