One senior source told the BBC that Gwynne had reached agreement on a pension on Thursday – which would allow him to retire as an MP on medical grounds – but cautioned that while they believed Gwynne’s departure was highly likely, it was not certain that an announcement would come today.
There has been speculation Burnham would like to replace Sir Keir as party leader, however he would only be able to enter any leadership race as a Labour MP.
If the Gorton and Denton seat becomes available, Burnham would need approval to run from Labour’s National Executive Committee (NEC) a body which is generally seen as being supportive of Sir Keir.
Several Labour sources said they expected the NEC to object on the grounds that Burnham standing for Parliament would in turn trigger a by-election for the Greater Manchester mayoralty, which would be seen as a drain on party funds as well as politically risky.
It is also possible that the NEC would insist that there should be an all-women shortlist of possible Labour candidates for a by-election in the Commons because a majority of the party’s MPs are currently men.
But others in the party questioned whether, if the NEC blocked Burnham from standing, his allies among Labour MPs could force party officials to overturn that decision.
If selected as Labour’s candidate, he would still have to win a by-election in Gorton and Denton at a time when the party’s popularity is low – although recent polling suggests Labour could hold on to the seat.
In the 2024 general election, Gwynne won with 18,000 votes. The Reform UK candidate came second securing 5,000 votes, just ahead of the Greens who picked up 4,810 votes.
Burnham has previously not denied he could challenge Sir Keir, saying: “I’m not going to rule out what might or might not happen in the future.”
Asked about Gwynne’s potential resignation, Health Secretary Wes Streeting said: “I’m aware he’s had some very serious health challenges. And you know, for all of the other challenges he’s gone through and some of the difficulties he’s had, I wish him and his family well.
“Whether or not Andy will throw his hat into the ring, is for Andy to consider, and ultimately for party members to decide but we need strong candidates.”
“Whether it’s in government nationally, or whether it’s leading the city and the region locally, he makes a massive impact and makes a really big difference.”