Keir Starmer is now grappling with escalating discord within the Labour Party regarding Andy Burnham, as irate Labour MPs caution the Prime Minister against obstructing the Manchester mayor’s potential return to Westminster, even if it leads to a leadership showdown.

Today, Labour’s National Executive Committee (NEC) is set to determine whether Mr. Burnham, who brands himself as the ‘King of the North,’ can contest an impending by-election following his last-minute announcement to enter the race.

This decision places Sir Keir in a precarious situation. Should his supporters permit Mr. Burnham to run for the Gorton and Denton seat, vacated by the disgraced former minister Andrew Gwynne, it could ignite a fierce leadership battle within the party.

Conversely, preventing his candidacy might exacerbate existing internal divisions and portray the Prime Minister as lacking resolve.

As the Mayor of Manchester, Mr. Burnham required NEC approval to participate in the by-election, a request he submitted just before the 5 p.m. deadline yesterday.

Today, key officials will deliberate on his eligibility, amid speculation that he might be excluded by a requirement for an all-female or all-BAME candidate list.

The committee is led by Sir Keir’s Home Secretary Shabana Mahmood. She today told Sky News she would remain impartial, but added: ‘I don’t think the country would forgive us if we indulge in a psychodrama.’

However senior figures like Ed Miliband and Sadiq Khan have backed Burnham and MPs went public to warn Keir and his allied to get out of the way. 

Justin Madders, who was a minister until he was sacked by Sir Keir in a reshuffle last year, said: ‘The overriding consideration for the party should be who is best placed to win and represent the people of Gorton & Denton – no stitch ups, no second guessing what might happen down the line. 

‘We need our best players on the pitch and the PM needs the best serving in his Government.’

However other leading figures questioned Mr Burnham’s motives for running. Lord Walney, a former Labour MP, likened the mayor and his allies to comedy character Alan Partridge with their ‘football metaphors’.

He added: ‘Andy Burnham’s supporters shouldn’t treat Labour members like idiots with this ”don’t leave your best player on the bench” argument about needing him to stop another Reform MP getting into parliament. 

‘The only reason that risk exists is because Andy wanted a by-election now. The mayorality of Greater Manchester is not ”the bench”.’

The Mail on Sunday understands Burnham made his approach after securing the backing of more than 100 Labour MPs, which would be enough to trigger a formal challenge to the PM if he returns to Parliament. 

Mr Burnham’s backers fear that Sir Keir’s absence on a trip to China this week could embolden the NEC to block his rival. 

Mr Burnham posted his letter to the NEC on social media site X at precisely 5pm today. In it, he said it was a ‘difficult decision’ but that he had given ‘careful thought’ to the best interests of the Labour Party and of Manchester.

And despite the divisive effects his manoeuvres are likely to have, he said he wanted to run a ‘hopeful and unifying campaign’.

Mr Burnham insisted: ‘I would be there to support the work of the Government, not undermine it, and I have passed on this assurance to the Prime Minister.’

Mr Burnham’s potential route to the leadership was opened when Mr Gwynne quit as MP last week.

It came a year after The Mail on Sunday revealed the MP was part of a WhatsApp group called Trigger Me Timbers that shared vile racist, sexist and anti-Semitic jokes. No 10 sacked him as Health Minister and he was suspended from the Labour Party.

The Mail on Sunday previously revealed in December that Angela Rayner (pictured on September 25, 2024) had ‘done a deal’ to be Mr Burnham’s running mate.

Announcing he was leaving the Commons, Mr Gwynne cited long-term health problems ‘exacerbated by the impact of last year’s events’.

If he was elected as an MP, Mr Burnham would be in a position to mount a leadership challenge against Sir Keir –likely to be triggered if Labour suffers the catastrophic losses it is expected to sustain at the local elections in May.

The MoS revealed in December that Angela Rayner had ‘done a deal’ to be Mr Burnham’s running mate.

Health Secretary Wes Streeting is regarded by Mr Burnham’s supporters as his only credible opponent in the event of a leadership contest.

The NEC is facing pressure to allow Mr Burnham to stand.  Energy Secretary Ed Miliband told the Fabian Society conference today: I very much hope that the local party will have the option of picking Andy as a candidate.’

Last week, Labour MPs told the MoS Mr Miliband will support Mr Burnham’s expected challenge on the understanding he will become Chancellor if Mr Burnham wins. London Mayor Sadiq Khan also backed Mr Burnham’s bid to stand as an MP, saying: ‘I’m a firm believer in the best team having all the talent playing for them.’

And Labour’s deputy leader Lucy Powell – a long-term thorn in Sir Keir’s side – said the decision on whether Mr Burnham should be the candidate ought to be ‘up to Andy and the local members’.

Writing on X, Chris Webb, MP for Blackpool South, said: ‘Our members are the lifeblood of our party and the NEC exists to serve them, not factions. Blocking Andy Burnham from Gorton & Denton will have serious lasting consequences. When you’re 2-0 down at half time, you bring on the super sub to help the team win.’

Health Secretary Wes Streeting (pictured on January 13) is regarded by Mr Burnham’s supporters

Kate Osborne, MP for Jarrow and Gateshead East, added: ‘We do not need factionalism before party – excluding Andy Burnham if he wants to stand would be a mistake & very weak.’

Others, however, appeared determined to block Mr Burnham. One member of the NEC reportedly told the BBC Newsnight’s Matt Chorley: ‘He will not be the candidate if I’ve got anything to ****ing do with it. Not a chance.’

Labour MP Graham Stringer accused Mr Burnham of ‘taking a big risk with his own career and the future of Labour in Manchester’.

Applications to stand as Labour’s by-election candidate close at midnight tonight.

In a rapid timetable, which critics believe is deliberately short to stymie Mr Burnham, a longlist of candidates, probably six, will be drawn up on Monday by a selection panel, shortlisting interviews will be held on Tuesday and hustings and selection will take place next Saturday.

Labour insiders estimate it could cost the party £1.5 million to organise and fight both a Westminster by-election and a ballot for the Greater Manchester mayoralty.

Even if the NEC allows him to fight the by-election, Mr Burnham will face a strong challenge from Reform and the Green Party.

An exclusive analysis commissioned by the MoS, which takes into account latest polling data, predicted that the seat could fall to the Greens.

But the study also shows that Reform would win if the Tories agreed not to stand – a forecast that will fuel calls for the parties on the Right to unite.

Analysis shows the two parties would gain 81 more seats between them if they entered a pact against the Left at the next general election.