Labour MP Josh Simons will resign his Greater Manchester Makerfield seat, triggering a by‑election.
The vacancy creates a pathway for Mayor Andy Burnham to re‑enter Parliament and potentially contest Labour leadership.
Burnham holds the only net‑positive approval rating among voters, making him the preferred left‑wing leadership candidate.
Prime Minister Keir Starmer may face a leadership challenge as Burnham’s return raises stakes for his tenure.