The United Kingdom could soon have its seventh prime minister in ten years. After Andy Burnham's landslide victory in the Makerfield by-election, Labour MPs are openly calling for Sir Keir Starmer to step down, and the mechanisms for replacing a sitting prime minister are once again under the spotlight. While the specific drama involves Labour's internal rules, the process is a fundamental feature of the UK's parliamentary system: a prime minister serves only as long as they command the confidence of the House of Commons and their own party. If a prime minister loses the backing of their party's MPs, they can be forced out through a leadership challenge, even without a general election.
At the centre of the current crisis is Andy Burnham, the Mayor of Greater Manchester, who won the Makerfield by-election with a convincing majority. This victory has given Labour MPs hope that Burnham could revive the party's fortunes, which have slumped since Starmer's landslide general election win in 2024. More than 100 Labour MPs have publicly called for Starmer to resign. Under Labour's rules, a leadership challenge requires 81 MPs (20% of the Parliamentary Labour Party) to nominate a challenger. Burnham is expected to easily surpass that threshold. If he becomes the only candidate with the required backing, he would be elected by acclamation — similar to Gordon Brown in 2007 — without a vote of party members. However, Starmer has said he will stand in any contest, which would guarantee a ballot of members and could prevent a coronation.
“How Labour can replace Keir Starmer with Andy Burnham after the Makerfield by-election.”
Leadership challenges are rare but not unprecedented in UK politics. The last time a sitting prime minister was replaced mid-term by their own party was in 2016 when Theresa May succeeded David Cameron after the Brexit referendum, and again in 2019 when Boris Johnson took over from May. Before that, Gordon Brown replaced Tony Blair in 2007 without a contest. The process differs by party; for Labour, a challenger needs nominations from 20% of MPs, while the Conservatives require a vote of no confidence triggered by 15% of MPs. Once a new leader is elected, they automatically become prime minister, as the monarch appoints the person who can command a majority in the Commons.
For UK readers, this matters because the next prime minister will take office without a general election. The change could happen within weeks, and with it, major policy shifts. Burnham has already floated ideas like a land value tax, and as a former health secretary, he will be under pressure to address the NHS crisis. The leadership contest also raises questions about electoral legitimacy — critics argue that voters chose Starmer in 2024, not Burnham. Yet the system allows parties to change leaders between elections, and many argue that if a party believes a new leader can win the next election, it is democratic for them to make that switch.
Q: How can a prime minister be removed without a general election? A prime minister can be removed by their own party through a leadership contest, or by losing a vote of confidence in the House of Commons. If the party elects a new leader, that person automatically becomes prime minister. A no-confidence vote requires a simple majority in the Commons and would trigger a general election unless another party can form a government.
Q: What is the difference between a by-election and a general election? A by-election is a single constituency election held between general elections, usually when an MP resigns or dies. It can signal national political trends but only affects one seat. A general election elects all 650 MPs and determines the government. By-elections can prompt leadership changes if they reveal a party's weakness or strength, as the Makerfield result has done for Labour.
Q: Why did Andy Burnham's win in Makerfield cause such a crisis for Starmer? Makerfield was a safe Labour seat, but under Starmer the party had suffered heavy losses in local elections and a wipe-out in Wales. Burnham's victory showed he could defeat Reform UK, the party seen as Labour's biggest threat. It convinced Labour MPs that Burnham, not Starmer, is the best chance to win the next general election, leading to a rapid loss of confidence in the prime minister.
The immediate future depends on whether Starmer can gather enough support to survive a leadership ballot. He has indicated he will fight on, but the momentum is strongly against him. If a contest is triggered, the Labour Party's National Executive Committee will set a timetable for nominations and voting. Expect a decision within weeks, possibly days. Burnham's supporters are pushing for a swift coronation to minimise internal damage, while Starmer's team insists on a full membership vote. Whatever happens, the UK is likely to have a new prime minister before the summer is out.