On 22 June 2026, Sir Keir Starmer announced his resignation as Labour leader, triggering a contest to choose the next prime minister. The move comes after devastating local and devolved election results in May, a series of ministerial resignations, and dire poll ratings that left Starmer with only 15% of voters thinking he can speak for the nation. Under the UK's unwritten constitution, when a prime minister resigns, the governing party selects a new leader who then becomes PM. This explainer walks through how that process works, who is in the running, and what it means for you.
The basics are straightforward: Labour's rulebook sets out the rules for electing a new leader. Candidates must be nominated by 81 Labour MPs and either 32 of Labour's 634 local branches or three affiliated organisations (including two trade unions). If more than one candidate clears that threshold, a vote among party members and affiliated trade union supporters decides the winner. The winner becomes Labour leader and, because the party is in government, prime minister. Sir Keir has said he will remain as PM until his successor is chosen.
“Explains the UK process for choosing a new prime minister after Keir Starmer's resignation.”
The frontrunner is Andy Burnham, the former Greater Manchester mayor who recently returned to Westminster by winning a by-election in Makerfield with an increased majority over Reform UK. He has confirmed he will stand. Burnham's main rival was initially expected to be Wes Streeting, but Streeting resigned as health secretary after the May elections. Other potential candidates have not yet declared. The contest timeline, announced by Starmer, gives hopefuls between 9 and 16 July to gather the required nominations. Parliament is due to return from its summer recess on 1 September, which is the likely deadline for a new leader to be in place.
This process matters for UK readers because the next prime minister will inherit a government with low public trust and a series of urgent challenges. Starmer's resignation followed mounting pressure over his appointment of Peter Mandelson as US ambassador, the election losses, and a row over defence spending that led to Defence Secretary John Healey's resignation. Polling from the New Statesman shows Starmer is the least liked of any recent prime minister at this stage of their premiership, with only 15% of voters thinking he can speak for the nation. Meanwhile, former senior Whitehall official Helen MacNamara has warned that Burnham's team lack the “urgency and ruthlessness” needed for a smooth transition into government, citing informal job conversations rather than a clear governing plan. The SNP has also called on Burnham to give “straight answers” on his Downing Street plans.
Q: How long does the leadership contest take? The official timetable has not been announced, but Sir Keir Starmer said candidates have between 9 and 16 July to secure nominations. A vote among members would follow if more than one candidate qualifies, with the aim of having a new leader before Parliament returns on 1 September.
Q: Can Andy Burnham become prime minister without a general election? Yes. In the UK, the prime minister is not directly elected. When a party wins a general election, its leader becomes PM. If the leader resigns, the party can choose a new leader who automatically becomes prime minister without a general election. Burnham would take over as PM as soon as he is elected Labour leader.
Q: What happens if no candidate gets enough nominations? If only one candidate clears the threshold of 81 MPs and the required local or affiliate support, they are elected unopposed and become leader without a membership vote. Currently, Burnham is the only declared candidate and is widely seen as having the necessary support.
What happens next depends on how quickly the contest unfolds. If Burnham is the sole candidate, he could become prime minister by late July. If others enter the race, a membership ballot will take place over the summer, with the winner announced before 1 September. Either way, the new prime minister will face immediate questions about defence spending, public trust, and the party's readiness to govern after a tumultuous few months.