Andy Burnham will face an enormous by-election challenge from Reform UK if the "King of the North" mounts a bid to become Prime Minister, allies of Nigel Farage have told GB News.
The Greater Manchester Mayor, who first stood for the Labour leadership in 2010, is mulling over a return to Westminster after leaving the House of Commons in 2017.
Mr Burnham was initially blocked by Labour's National Executive Committee from standing in February's Gorton & Denton by-election, with the Greens later securing a seismic victory and Reform UK ending up in a distant second place.
Sir Keir Starmer's leadership rivals are now circling No10 after more than 80 Labour MPs called on the Prime Minister to step down.
Despite being the public's pick for Sir Keir's successor, Mr Burnham needs a sympathetic Labour MP to step down and hope Labour's NEC will not block him from standing again.
However, Reform UK sources have warned Mr Burnham faces an uphill struggle to return to the House of Commons.
"We would fight very hard indeed," one insider told GB News.
Another Reform UK veteran added: "Given Labour were demolished across the former Red Wall, there are no 'safe' Labour seats left.
Andy Burnham is searching for a seat to return to the House of Commons
|PA
"Andy Burnham and Labour ministers show their contempt for the electorate by thinking they can swap out one of their MPs and crown a new Prime Minister. Voters will teach them a brutal lesson."
A third warned: "We won every seat in Angela Rayner's patch last week. Ask her if there are any safe Labour seats."
Zack Polanski's Green Party is also understood to be preparing to launch a huge by-election campaign should Mr Burnham seek to return to the House of Commons.
Mr Burnham, who served as the MP for Wigan between 2001 and 2017, would likely contest a by-election at a time of historic unpopularity for the Labour Party.
Sir Keir's premiership is on the brink after losing 1,498 councillors in the 2026 Local Elections, with Reform UK gaining 1,452 wards and the Greens picking up an extra 441 seats.
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Sir Keir Starmer and Andy Burnham have endorsed one another in respective leadership bids
| PAReform UK secured 30 per cent of the vote across Greater Manchester on May 7, with Labour being reduced to 23 per cent and the Greens breathing down Sir Keir's neck on 19 per cent.
Wigan, which includes Mr Burnham's old patch of Leigh, witnessed a Labour collapse of 22 seats as Reform UK picked up 24 out of the 25 wards up for grabs.
Reform UK also surged in Bolton, Bury, Oldham, Rochdale, Tameside and Salford.
Mr Burnham, who was born in Merseyside, could also struggle further down the M62 after Reform UK made inroads in Halton, Knowsley, Sefton, and St Helens.
St Helens South & Whiston MP Marie Rimmer dealt a blow to Mr Burnham's leadership ambitions after vowing not to trigger a by-election.
Reform UK was campaigning in Greater Manchester over the weekend | X/LEE ANDERSONHowever, it is now being suggested that Mr Burnham has found a seat in Greater Manchester and arrived in London earlier today as chaos engulfs Downing Street
Heywood & Middleton South MP Graham Stringer dismissed speculation he was looking to give up his seat.
Meanwhile, rumours swirling around Westminster suggest Oldham West, Chadderton & Royton MP Jim McMahon could clear a path for Mr Burnham.
Mr McMahon won his seat with a majority of 4,976 at the 2024 General Election.
The seat is now considered a firm target for Reform UK in the North West of England.
Nigel Farage secured a seismic victory in the 2026 Local Elections
| PAMerlin Strategy founder Scarlett Maguire suggested Mr Burnham was Labour's best bet for a by-election victory.
The polling guru said: "There are practically no 'safe' seats left, but an Andy Burnham run in a Greater Manchester seat is about as good as it gets for Labour."
There are also concerns that Mr Burnham's leadership ambitions could seal yet another Reform UK mayoral victory if he vacates his post in Greater Manchester.
The 56-year-old had previously appeared to commit to his third term as Greater Manchester Mayor.
Sir Keir Starmer is battling to save his political career
| GETTYSpeaking to GB News at the 2024 Labour Party Conference, Mr Burnham said: “I am committed to my third term, absolutely. I’m not planning to head back to Westminster any time soon.”
However, the former Health Secretary stopped short of ruling out a return to the House of Commons altogether.
Ex-Deputy Prime Minister Angela Rayner, who held a secret meeting with Mr Burnham last month, extended an olive branch by claiming her Manchester neighbour "should never have been blocked" by the NEC.
The NEC is now increasingly inclined to let Mr Burnham run, having voted 8-1 against his candidacy in February.
Wes Streeting and Angela Rayner have both been tipped to challenge Sir Keir Starmer after May 7 | GETTYSir Keir, who is maintaining he will stay on in No10 and avoid becoming Labour's shortest-serving Prime Minister, said on Monday: “Any future decision is for the NEC. Andy is doing a great job as mayor in Manchester and I actually work really well with Andy.”
Mr Burnham was bounced into rushing ahead with his plans after little-known Labour MP Catherine West emerged as a stalking horse to trigger a leadership contest.
Despite Ms West later reining in her ultimatum, more than 80 Labour MPs have now called on Sir Keir to step down, with 81 being required to back a candidate to trigger a leadership contest.
Health Secretary Wes Streeting looks poised to mount his own challenge to the Prime Minister, with Ms Rayner's position still looking difficult given her council tax dispute over her £800,000 flat in Hove.