On a Thursday night in June, a Greater Manchester mayor confirmed what many had suspected: if he wins a by-election, he will run to become the next Labour leader and prime minister. Andy Burnham's announcement on BBC Question Time turned the subtext of the Makerfield by-election into text, setting off a chain of events that could reshape British politics. But what exactly is a Labour leadership contest, and how does one get started?
The Labour leadership is decided by a vote of party members and affiliated supporters. To trigger a contest, a challenger must be an MP and secure the backing of 81 Labour MPs (20% of the parliamentary party). The current leader, Sir Keir Starmer, became prime minister in 2024 and has defied calls to step down after poor local election results. No formal challenge has been launched against him, but Burnham and health secretary Wes Streeting have both said they would enter any contest that does arise.
“Explains Andy Burnham's Labour leadership ambitions and the process to challenge Sir Keir Starmer”
Burnham, the mayor of Greater Manchester since 2017, is standing in the Makerfield by-election on 18 June. The seat became vacant when the previous Labour MP, Josh Simons, stepped down to allow Burnham to run. The by-election is expected to be a close race between Burnham and Reform UK candidate Robert Kenyon, a plumber and local councillor. Kenyon has criticised Burnham as a "career politician" and accused him of using the seat as a "stepping stone".
Burnham's pitch goes beyond personal ambition. He has proposed nationalising Thames Water, England's largest water company, which serves about a quarter of the population. He argues that since privatisation under Margaret Thatcher, the company has been loaded with about £20bn of debt and is now close to collapse. "Public ownership is absolutely an option," he told the Guardian, and said Thames Water "should be" nationalised. He has met water campaigners including former Undertones frontman Feargal Sharkey, an outspoken advocate for nationalisation.
For UK readers, this matters because it offers a glimpse of a possible future government. A leadership contest would force a debate about the direction of the Labour Party and the country. Burnham's platform—which emphasises devolution, public ownership, and a break from Westminster "point-scoring"—could reshape policies on water, transport, and local government. The outcome of the Makerfield by-election on 18 June will be a crucial first step.
Q: How can a Labour leadership contest be triggered? A challenger must be a sitting MP and win the support of 81 Labour MPs. If that threshold is met, a ballot of party members and affiliated supporters is held. No MP has yet reached that number, though Burnham and Streeting have indicated they would enter a contest if one begins.
Q: What is the Makerfield by-election and why is it important? Makerfield is a constituency in Greater Manchester that became vacant when Labour MP Josh Simons resigned to allow Burnham to run for Parliament. The by-election on 18 June will determine whether Burnham can re-enter the Commons and become eligible to challenge Starmer. The result is seen as a proxy for Labour's popularity and Burnham's electoral strength.
Q: What are Andy Burnham's key policies? He supports nationalising Thames Water and has called for greater public control over water companies. As mayor, he has championed devolution and a "Manchesterism" approach—pragmatic, localist politics. He has criticised the "career politician" label and argues for problem-solving over point-scoring. He also praised the Scottish model of publicly owned water.
What happens next? The Makerfield vote takes place on 18 June. If Burnham wins, he will be an MP and could then try to gather the 81 nominations needed to trigger a contest. Meanwhile, Prime Minister Starmer has said he will not walk away from the mandate he was given two years ago. The coming weeks will determine whether the Labour Party moves towards a leadership election—and a possible new prime minister.