For weeks, Andy Burnham’s supporters had told MPs to “hold the line”, that he had a seat in parliament in his sights and that he would be a contender in any leadership contest. That was never the full truth.

His path to No 10 – if he makes it – is littered with more failed attempts than almost any other politician. Two leadership contests, a block on a return in Gorton and Denton, and quite a few aggrieved MPs in the north west who have had to spend weeks batting off suggestions they will give their seats up for him.

By Thursday this week, with almost all the likely contenders ruling themselves out, Burnham’s backers in parliament were getting desperate. Only the tiniest handful of the Greater Manchester mayor’s closest advisers knew the truth: there was finally a seat coming which no one expected.

When Wes Streeting announced at 1pm on Thursday that he was resigning from Keir Starmer’s cabinet, it set off a bombshell ; outwardly, things did not look hopeful. Streeting had not launched a leadership bid, and Burnham still ostensibly had no seat in Westminster from which to make his own challenge.

Locked out of parliament, Burnham seemed to be no further on than when he made his last leadership tilt, which was ended by the Labour national executive committee’s refusal to let him run in the Gorton and Denton byelection.

The mood among his supporters was bleak. “It’s a shit cocktail,” said one. “We’re all doomed.” But Burnham, as some other famous northerners once said, got by with a little help from his friends. Behind the scenes, his team got to work and finally, on Thursday, an opportunity appeared.

“It was always a case of just sitting and waiting,” said one source close to Burnham. While there was not an obvious seat, the sense was that Labour’s dismal performance in Gorton and Denton, plus disastrous results in the local election, could “unlock that route back”.

The confidence of hindsight, however, masks what has been a fraught week for team Burnham. As the guessing game of who would give up their seat took hold in the parliamentary press gallery, names and refusals began to stack up.

Paula Barker, the MP for Liverpool Wavertree, said she would be delighted if a seat could be found for Burnham, but, asked by the BBC if she’d give up her own, the answer was: “No.” Five MPs whose seats had been linked to a Burnham leadership bid all refused to stand down.

Over the previous weekend, those close to the Burnham campaign are understood to have had a seat in mind, the Manchester Rusholme seat of Afzal Khan. But Khan is thought to have changed his mind, with some MPs suggesting interventions from No 10 played a part.

Marie Rimmer, the MP for St Helens South and Whiston, was said to hold the other seat in play. Not according to her. “I just said: ‘No, absolutely not,’” Rimmer told the Guardian when asked about being approached by allies of Burnham. “I was appalled, actually. Really insulted and disgusted.”

Behind the scenes, nerves were jangling. One Labour source said team Burnham had attempted to “bully people into stepping down” and had even offered the Greater Manchester mayoralty in exchange for a parliamentary seat. Khan was rumoured to have been offered a seat in the Lords. But he dismissed the suggestion, telling the Guardian: “There was never any question of me giving up my seat, it’s not true.”

By Tuesday, Burnham was on the west coast mainline in an effort to win over MPs and unions in person while negotiations intensified. Several MPs told Burnham they backed him, but were worried about the financial implications of losing their jobs.

Then a wildcard arrived out of nowhere. Talks opened with Josh Simons, the 32-year-old Makerfield MP who has long been disillusioned with Starmer and came to believe Burnham should be the next prime minister more than a year ago. The pair became close over the last two years, after Burnham, not Whitehall, came to his aide after major floods in Platt Bridge.

“I think being a constituency MP radicalised Josh to how broken the country is,” said one friend. “He is so young, it is such a sacrifice.”

Another close friend said: “Burnham knows how to advocate for the people and not for the system.”

Simons only began to seriously consider giving up his seat this week, the Guardian understands. The final decision was made after Burnham went to see Simons at home with his wife, Leah, an American economist who Simons met at Harvard and who has recently given birth to their third child. They spent two hours asking in-depth questions about Burnham’s plan for government, his economic strategy, his position on financial markets, and what he could really do in office.

Then, at 5.14pm on Thursday, a little over five hours after Streeting’s resignation, Simons announced he was stepping aside to pave Burnham’s way to Westminster.

But while the veteran politician has finally cleared the first hurdle, others remain. Labour’s majority in Makerfield was just 5,399 in 2024 and Reform UK won all the constituency’s wards in last week’s local elections. Nigel Farage has said his party will “throw absolutely everything” at the byelection, while the Greens have indicated they will properly contest it.

Burnham’s success was therefore existential, Simons told the Guardian. “The electoral story perfectly encapsulates the moral story; it’s the fight of our times,” he said.

“We are where the Democrats were in 2021, hurdling towards oblivion with an out-of-touch PM. It just needed something that could change the story. Burnham winning in Wigan, that does it.”

Just 25 minutes after Simons announced he would be stepping aside, Burnham confirmed he would run. “There is only so much that can be done from Greater Manchester,” he said in a statement. “This is why I now seek people’s support to return to parliament: to bring the change we have brought to Greater Manchester to the whole of the UK and make politics work properly for people.”

And, as the candidate took to the streets around his home for a jog in a vintage football shirt on Friday, the message was clear: he’s running.