Andy Burnham has cleared the first hurdle as he seeks to become an MP again after Labour’s governing body said it would approve his request to stand in the candidate selection process for the upcoming Makerfield byelection.

The Greater Manchester mayor has two years of his term remaining, which means there will also need to be a mayoral byelection if he stands. Under Labour rules, sitting mayors need the approval of the party’s national executive committee (NEC) to stand for Westminster. He would also need to be formally selected.

If he wins the byelection, Burnham is widely expected to challenge Keir Starmer for the party leadership. To do so, he would need the support of 81 Labour MPs, or 20% of the party in parliament.

Burnham was turned down by the NEC in February to stand in the Gorton and Denton byelection. But after the sitting Makerfield MP, Josh Simons, said on Thursday he would give up his seat in the hope that Burnham could enter Downing Street, which has a big sway over NEC decisions, the committee indicated it would not do so again.

In stark contrast to earlier this year, officers on the NEC are understood to have agreed by email with each other that any request for a waiver by Burnham would be approved. They did not even wait for an application by him.

Under a timetable agreed by NEC officers on Friday, the window for applications to stand in Makerfield opened immediately and will close at noon on Monday. Due diligence checks will conclude on the same day, as will a selection panel longlisting.

Selection panel shortlisting interviews will take place on Tuesday, before hustings. The NEC’s endorsement of the candidate is marked for 21 May. A Labour party spokesperson said: “Labour’s ruling body, the national executive committee has today given permission to Andy Burnham to stand in the candidate selection process in the forthcoming byelection for the Makerfield constituency.”

There had been widespread anger among Labour MPs and union backers in January when the 10-strong “officers’ group” of the NEC, including the prime minister, voted to reject Burnham’s request to seek selection for the Gorton and Denton byelection.

On that occasion, the committee said picking Burnham would require a hugely expensive and destabilising election to replace him as mayor of Greater Manchester less than halfway through his four-year term.

After the news that Burnham had been given the green light even before he had submitted an application, a member of the NEC told the Guardian: “Regardless of where people stand on the recent events in the party, we have got this byelection and he is our best shot of winning it, so we need to get behind him.”

Earlier on Friday, the former health secretary Wes Streeting joined those in the Labour ranks who have already backed Burnham running in the byelection, saying Labour needed “our best players on the pitch”.

Rupa Huq, the Labour MP for Ealing Central and Acton, said on X that it was the “right decision” for the NEC not to block Burnham.

“Party democracy must be allowed to thrive. Our members who pay their subs deserve respect and final say,” she added.