On 18 June, voters in the north-west English constituency of Makerfield will choose their next MP – and the result could shape the future of the Labour Party. At stake is not just a seat in Parliament, but the viability of a challenge to Prime Minister Sir Keir Starmer's leadership. The by-election was triggered when Labour MP Josh Simons stepped down, a move he said was to allow Andy Burnham, the Greater Manchester mayor, to run for Parliament and potentially mount a leadership bid. Burnham has made no secret of his ambitions: he told a BBC Question Time special that if he wins, he would seek to enter any Labour leadership contest. But the contest is tight, with Reform UK candidate Robert Kenyon polling within ten points – and among men, the race is neck and neck.
This by-election is a test of Labour's strength in a seat that, according to demographic analysis by Britain Predicts, is naturally favourable to Reform even when Labour wins nationally. A poll by Survation gave Burnham a ten-point lead overall, but that masks a gender divide: Burnham's lead among women is emphatic, while among men he is level with Kenyon. The Reform candidate has drawn criticism for comments on abortion and about Carol Vorderman, which may be mobilising women voters. Voter uncertainty is unusually low among women in the constituency, suggesting strong opinions. Meanwhile, Burnham's record as mayor is under scrutiny. He points to economic growth, public transport and education achievements, but the abandoned plan for a Greater Manchester clean air zone that would have charged polluting vehicles £60 a day remains a sore point for some local voters.
“The Makerfield by-election explained: what it means for Labour leadership and UK politics.”
For UK readers, this by-election matters because it is a live demonstration of how internal party dynamics and by-election performances can trigger or stall leadership challenges. Under Labour rules, any challenger must be an MP and have the backing of 81 Labour MPs. Burnham cannot even enter the race unless he wins Makerfield first. Health Secretary Wes Streeting has confirmed he would enter any contest, and has encouraged support for Burnham to ensure a 'proper contest'. But Starmer has so far resisted calls to resign, with his spokesperson saying he 'will not walk away from the mandate he was given just two years ago'. Justice Secretary David Lammy also backed Starmer, citing his 'mandate from the British people less than two years ago'. The outcome in Makerfield will therefore be read as a proxy for Starmer's authority.
## Key questions answered
Q: What is a by-election and why is Makerfield happening? A by-election is a special election held when an MP leaves Parliament between general elections. In Makerfield, the by-election was called after Labour MP Josh Simons stepped down to allow Andy Burnham to run for Parliament, with the goal of launching a leadership challenge against Sir Keir Starmer.
Q: How can a Labour leader be challenged? To trigger a Labour leadership contest, a challenger must be a sitting MP, win the backing of at least 81 Labour MPs (20% of the parliamentary party), and then face a vote of all party members. No formal challenge has yet been launched against Starmer.
Q: Why is the gender divide in polling significant? Reform candidate Robert Kenyon has made controversial comments on abortion and about Carol Vorderman, which may alienate women voters. Polling shows Burnham with a large lead among women, while men are evenly split. This could be key to the by-election result and may test whether misogyny is a vulnerability for Reform UK.
## What happens next The Makerfield by-election takes place on 18 June. If Burnham wins, he will become an MP and could then seek the 81 nominations needed to trigger a leadership contest. Starmer has indicated he would fight any such challenge. If Burnham loses, his leadership ambitions would be stalled, and the question of Starmer's future would remain unresolved, at least for now.