Ministers are discussing a 'Trojan Horse' plot to line up Andy Burnham to replace Keir Starmer in the wake of the local elections.

Preparations are in place for a sympathetic north west Labour MP to step aside as soon as next week to open up a potential route back to Westminster for the Great Manchester mayor.

Ministers would then demand that Sir Keir drop his opposition to Mr Burnham's return as the price of their continued support.

In return, Mr Burnham would be asked to make a public statement of loyalty to Sir Keir, which would prevent him from mounting an immediate leadership challenge.

Supporters of the idea argue it would avoid plunging Labour into a chaotic snap leadership contest – and give the PM a final chance to show whether he can turn round Labour's fortunes.

But it would also leave Labour MPs with a ready-made successor if Sir Keir falters in the coming months.

Cabinet Ministers advocating the plan say it will be presented to Starmer as the best opportunity to save his premiership.

According to one source, 'the attraction for Keir is there is no guarantee Andy will win the by-election. If he wants to be the candidate he will need to sign a loyalty oath to the Prime Minister. And it buys Keir a bit more time to see if he can turn things round'.

Another Burnham-backing MP said: 'It's increasingly clear that Andy is the answer. Starmer can't keep on blocking him forever. And once he's inside the walls then – like the Trojan Horse – he is in place and ready if the situation becomes unsustainable.'

A third source said: 'Andy would effectively be a Trojan Horse. As soon as he's in [the Commons] all the in-fighting and manoeuvring would end, because then there's a clear successor to Keir in place.

'So it staves off an immediate civil war. But for Keir it gives him one final chance to see if he can pull off a miracle and shift the polls. And if he doesn't take it, then Andy just steps up without too much drama.'

The Trojan Horse was a mythical wooden construction used by Greek forces to smuggle in soldiers during the siege of Troy. It has become a metaphor for a malign gift.

Downing Street is braced for a potential leadership challenge in the wake of Thursday's local elections which are expected to result in a Labour wipeout.

However, health secretary Wes Streeting is said to be reluctant to make the first move for fear of damaging his chances. Angela Rayner is also nervous about launching a direct challenge, amid concerns that her support at Westminster is already on the decline.

Allies of the PM have dismissed the idea he would sanction a return for Mr Burnham just three months after blocking him from standing in the Gorton and Denton by-election in Greater Manchester.

And they have rubbished reports at the weekend claiming that Labour's ruling National Executive Committee, which formally blocked him last time, has now 'flipped' to support him.

A Labour source said: 'Andy cannot name a single member of the NEC who he has won over since he was last rejected. His 'credible' plan is based on fantasy.'

Bootle MP Peter Dowd and St Helens MP Marie Rimmer are both said to be willing to step aside for Mr Burnham, although both have denied publicly that they have any plans to quit.

However, with Reform expected to poll strongly across Labour's Red Wall on Thursday, any by-election would be fraught with danger.

Steve Wright, general secretary of the Labour-affiliated Fire Brigades Union said the Prime Minister would be a 'sitting duck' after Thursday's elections, which are expected to see Labour battered in Wales and Scotland as well as losing up to 2,000 council seats across England.

Mr Wright said Labour would have fared better if Sir Keir had quit 'a couple of months ago'. He added: 'I think he will go. I think there will be calls for him to go. It's inevitable now, isn't it? I think he's a bit of a sitting duck.'

But communities secretary Steve Reed told Times Radio that most Labour MPs were 'sick and tired of all of this psychodrama'.

He added: 'The whole notion that we would copy the Conservatives and go doomscrolling through leaders in a way that means the government is completely incapable of dealing with the things that matter the most to the British public is an absolute nonsense. And I'm not going to engage in it, and most of our MPs would not engage in it either.'