Andy Burnham wins Makerfield by-election, can now force Labour leadership contest against Keir Starmer

The by-election result

Andy Burnham, the mayor of Greater Manchester, won the Makerfield by-election early Thursday, defeating Reform UK candidate Robert Kenyon by nearly 10,000 votes. Turnout was 58.78 percent. The vacancy opened after Labour MP Josh Simons resigned, following the party's heavy local election losses, to enable Burnham's return to Westminster. The calculation, that a Burnham win would launch a leadership challenge, was risky: Reform could have taken the seat, but the gamble paid off. Burnham will vacate the mayoralty to serve as MP.

Starmer's eroding position

Prime Minister Keir Starmer has faced intensifying internal pressure for months, punctuated by the departures of several ministers, most recently Defence Secretary John Healey. Tabloid front pages have depicted Starmer as 'on the brink' and Westminster in chaos. The immediate trigger was Labour's poor showing in local and regional votes in England, Scotland and Wales in early May, where Reform made gains. Starmer has repeatedly declined to resign or outline an exit, invoking his sweeping 2024 general election victory and the mandate to steer the country through crisis.

Burnham's profile and ambitions

Burnham, 56, is a figure of the party's moderate left. His tenure as mayor of Greater Manchester was marked by a hands-on, can-do style. He left Parliament roughly ten years ago after a failed leadership run, but now, with an MP's seat again, a new bid is widely expected. Supporters hope his appeal will unite the party and displace Starmer.

The mechanics of a challenge

Labour rules require any challenger to secure the backing of 20 percent of the parliamentary party, currently 81 MPs. If Burnham gathers those signatures, a full membership ballot ensues, with Starmer automatically listed as the incumbent. Former health secretary Wes Streeting, who also stepped down from the cabinet, is seen as another contender. The process is not swift: it could stretch for weeks or even months, consuming the party in an internal campaign.

Reform UK's opportunity

The extended factional struggle plays into the hands of Reform UK and its leader Nigel Farage, who has long agitated against the government and openly aspires to the premiership. With the next general election fixed for 2029, the prospect of Labour tearing itself apart gives Reform time to build momentum. The party's strong by-election showing underscores its capacity to attract disaffected voters.