Keir Starmer faced warnings last night that blocking Andy Burnham from a by-election run could increase the likelihood of a leadership challenge.

In a day filled with political tension, the Prime Minister was accused of avoiding a showdown by actively preventing the Greater Manchester mayor from pursuing a seat as a Member of Parliament.

Starmer’s decision threatens to spark internal conflict within the Labour Party, as he confronted influential party members who openly supported Burnham’s return to the national political stage.

Andy Burnham, breaking his silence last night, criticized the manner in which the Labour Party is being managed, particularly expressing frustration that the press was informed of the decision before he was.

In a post on X, Burnham expressed his disappointment with the National Executive Committee’s (NEC) decision, voicing concerns over how this could affect upcoming elections.

He further commented, “The fact that the media was informed of the NEC decision before I was says a lot about the current state of the Labour Party’s management.”

‘You would think that over 30 years of service would count for something, but sadly not.’

The move to block him from fighting the Gorton and Denton by-election has infuriated Labour MPs who warned Sir Keir that it would ‘hasten his demise’ and increase the chances of a leadership challenge.

Keir Starmer, pictured at the Arsenal match on Sunday, was warned last night that the by-election block on Andy Burnham has made it more likely he will face a leadership challenge

Mr Burnham, pictured walking with his mother, broke his silence to criticise the ‘way the Labour Party is being run’ after revealing the media was told about the decision before he was

Amid the furore, Sir Keir was spotted in the stands at Emirates Stadium watching his football team Arsenal lose 3-2 at home to Manchester United yesterday.

Labour faces difficult local elections in May in which the party is expected to perform disastrously in Wales and Scotland and lose seats to Reform UK.

There is also fury that by blocking Mr Burnham, arguably Labour’s best candidate for the seat, the party has gifted it to Nigel Farage’s party.

Karl Turner, Labour MP for Kingston upon Hull East, said the decision to sabotage Mr Burnham’s bid ‘provides more chance of a challenge’ if the party loses the by-election.

Labour MP and former shadow chancellor John McDonnell said he had sent a message to the PM to tell him that ‘if he thinks this strengthens his position, I think it will used to hasten his demise if he’s not careful’.

And former Labour MP Diane Abbott, now an independent, added: ‘If the results in May are as bad as we all think they’re going to be, a challenger will emerge from somewhere.’

In a major political risk yesterday, Sir Keir made the case against Mr Burnham quitting his role and running for the seat. He and an overwhelming majority of a panel of the party’s ruling board voted against the prospect of rerunning the Manchester mayoral elections.

Any directly elected Labour mayor must seek the permission of the party’s National Executive Committee (NEC) before standing in a by-election. Labour said the party had denied this to ‘avoid an unnecessary mayoral election, which would use substantial amounts of taxpayers’ money and resources that are better spent tackling the cost-of-living crisis’.

Jostling among the PM’s hopeful successors will begin again in earnest, with Angela Rayner likely to lead the charge

The decision was made in a 45-minute meeting of ten members of the NEC led by Home Secretary Shabana Mahmood, who abstained from voting. The panel, including the Prime Minister and Solicitor General Ellie Reeves, the sister of Chancellor Rachel Reeves, voted 8-1 in favour of blocking Mr Burnham.

But, in a sign of divisions within the party, Labour’s deputy leader Lucy Powell was his only ally, casting the sole vote of support.

Labour sources said the decision was taken to prevent a costly and toxic battle for the Manchester mayoralty against Reform.

There have been suggestions that the costs of running a mayoral election at the same time as the by-election would cost millions, with the last costing about £4.7million.

There were also major fears that Reform could take the mayoralty – the biggest prize yet for Mr Farage.

Mr Burnham said yesterday: ‘[On Monday] I return with full focus to my role as Mayor of GM, defending everything we have built in our city-region over many years.

‘I decided to put myself forward to prevent the divisive politics of Reform from damaging that. We are stronger together and let’s stay that way.’ The by-election race was triggered on Friday after disgraced former Labour minister Andrew Gwynne resigned on health grounds.

Mr Gwynne was suspended by Labour last year after The Mail on Sunday uncovered a series of offensive WhatsApp messages he had sent.

Allies of Health Secretary Wes Streeting believe he has the ‘solid’ support of almost half of Labour’s 404 MPs to challenge Sir Keir for the leadership 

The once-safe Labour seat is thought to be a three-way marginal between Labour, Reform and the Greens. The decision to block Mr Burnham has caused deep anger among Labour MPs including Jo White – head of the influential Red Wall caucus – who on Friday called for the North to decide.

It has also infuriated powerful union bosses, including Unison leader Andrea Egan who warned against ‘control freakery’ before the decision. She tweeted yesterday: ‘This isn’t the way any democratic organisation should be run. Now’s the time to unite our movement, not divide it.’

The row has opened up a North-South divide in the party and has the potential to plunge Labour deeper into civil war.

Jostling among the PM’s hopeful successors will begin again in earnest, with Wes Streeting and Angela Rayner likely to lead the charge.

Allies of the Health Secretary believe he has the ‘solid’ support of almost half of Labour’s 404 MPs to challenge Sir Keir for the leadership.

But former deputy PM Ms Rayner is often talked up as a contender, as is Energy Secretary Ed Miliband, who tops members’ polls.

Mr Streeting has made little secret of his desire to be Prime Minister at some point and has been linked with a challenge should Labour take a hammering in May’s local elections.