Manchester Mayor Andy Burnham has taken the first step toward a potential bid for UK prime minister, winning a Labour seat in the by-election for the Makerfield constituency in northwest England on Thursday, 18 June 2026.
A Leadership Ambition Takes Shape
Burnham — who has made no secret of his ambition to replace Keir Starmer as both Labour Party leader and prime minister — now joins Parliament as an MP. His election marks a crucial prerequisite: only sitting MPs can become prime minister or formally challenge for the Labour leadership.
The move comes amid growing internal pressure on Starmer following Labour’s worst-ever local election defeat in May — the largest loss suffered by a governing party in over three decades. Roughly one-quarter of Labour MPs have reportedly called on Starmer to step down.
Rules and Timelines for a Leadership Challenge
Under Labour Party rules, any leadership challenger must secure the formal backing of at least 20% of Labour MPs — currently 81 members, including the candidate themselves. Burnham is widely seen in polls as the frontrunner should a contest proceed.
If he chooses to launch a challenge soon, Burnham would likely need to announce it officially before 16 July, when Parliament breaks for its summer recess. Starmer automatically qualifies for re-election as party leader and has confirmed he will stand again.
Once candidates meet the parliamentary threshold, they must also win support from local party branches and affiliated trade unions. The full leadership election — open to all Labour members — could take two to three months to conclude.
Strategic Timing and Other Contenders
Burnham may delay his announcement until after the summer break. Doing so would allow him to focus on Manchester’s mayoral election — expected around late July — where he plans to campaign for his successor. It would also give him time to build relationships with newer Labour MPs elected since his 2017 departure from Parliament and to broaden his support base within the parliamentary party.
He is not the only potential challenger. Wes Streeting, who resigned as Health Secretary in May, has also indicated he may consider entering the race — adding further uncertainty to Labour’s leadership dynamics.