How Will A Labour Leadership Contest Work?

Keir Starmer's rivals are preparing to launch a contest for the Labour leadership (Alamy)

zoecrowther.bsky.social

5 min read14 May

A leadership contest to oust Keir Starmer as prime minister looks imminent, with Health Secretary Wes Streeting having resigned, an MP standing aside to allow Andy Burnham to potentially return to Parliament, and more than 90 MPs having called on Starmer to stand down or set out a timetable for doing so.

Starmer's rivals are lining up to launch a leadership contest. Streeting has published his letter to Starmer announcing his resignation from the Cabinet, writing that he had “lost confidence in your leadership” and that it would be “dishonourable and unprincipled” to stay in post.

Former deputy Labour leader Angela Rayner has said she had settled her unpaid council tax bill of £40,000, and her allies have briefed that she would be prepared to stand in any leadership contest if needed.

Labour Greater Manchester mayor Burnham – who served as a minister during the Blair and Brown governments – has also announced his intention to stand, but is not currently sitting as a Labour MP. However, a potential route for him to re-enter Parliament and run as leader has opened up. Labour MP and former minister Josh Simons announced on Thursday evening that he will stand aside as MP for Makerfield in Greater Manchester to allow Burnham to stand for the seat.

So far, Starmer has insisted he will not stand down, saying in a speech on Monday that doing so would “plunge the country into chaos”. In an appeal to his own MPs, he said that governments constantly changing their leadership had been “damaging”.

Should Starmer refuse to leave, but a contest is nonetheless triggered, he is automatically entitled to be on the ballot paper as the sitting Labour leader.

As a leadership challenge looks imminent, how will a contest work, and how long would it take?

The process for a Labour leadership election

There are two main paths to replacing a Labour prime minister, with the process differing significantly from that of the Conservative Party, which held multiple leadership elections during its time in power between 2010 and 2024.

A leadership contest can be triggered by either Starmer resigning or by another Labour MP gaining the support of 81 MPs – or 20 per cent of sitting Labour MPs – to challenge him for the leadership. Before 2021, an MP only needed the support of 10 per cent of the Parliamentary Labour Party to stand.

The candidates must then secure nominations from five per cent of Constituency Labour Parties or three affiliates comprising five per cent of Labour's affiliated membership (including two trade unions).

The final stage is a vote among party members and affiliates. An alternative vote system – also known as a preferential ballot – is used, in which the selectorate ranks their preferred candidates. Voters only have one vote. Votes are then redistributed by ranking until one candidate receives over 50 per cent of the vote; the candidate that reaches the threshold first wins the leadership contest, becoming Labour leader and prime minister of the United Kingdom.

Labour leadership contests can drag on for months. In practice, a full Labour leadership contest usually takes around 12 weeks.

The formal process under Labour’s current rules is as follows:

The leader resigns or is challenged
Labour’s National Executive Committee (NEC) sets the timetable
Candidates need nominations from MPs (candidates must reach the threshold of 81 nominations, 20 per cent of the current Parliamentary Labour Party)
Candidates then need to win nominations from the Constituency Labour Parties and affiliates
The third stage is the vote among members and affiliates
The result is announced

The NEC has significant flexibility over the nomination thresholds, the timing of voting ballots, the schedules for hustings and the overall pace of the contest.

How long did previous Labour leadership contests take?

2020 Labour Party leadership election (when Keir Starmer succeeded Jeremy Corbyn) – about 16 weeks from resignation announcement to result, or about 13 weeks from formal opening to result
2016 Labour Party leadership election (when Corbyn was challenged by Owen Smith) – about 13 weeks from revolt to result
2015 Labour Party leadership election (when Corbyn was elected as leader) – about 18 weeks. One of Labour’s longest contests in the past few decades
2010 Labour Party leadership election (when Ed Miliband beat his brother, David Miliband, to the leadership) – about 19 weeks. Again, a very long contest because it followed a general election defeat and involved a full summer campaign

The process for a parliamentary by-election

Burnham is one step closer towards potentially returning to Parliament, after Makerfield MP Simons agreed to stand aside. However, questions remain over whether the NEC would permit Burnham to stand as the Labour candidate, having blocked him from doing so in the Gorton and Denton by-election in February.

Even if Burnham does stand as the candidate, he would still need to carry out the campaign and win the seat in time before the nominations open for the Labour leadership contest.

Polling day for a parliamentary by-election is usually held about four to eight weeks after an MP announces their intention to stand down.

The process for a parliamentary by-election is as follows:

The seat would become vacant
Labour whips would need to move the writ
Burnham would need NEC approval as a candidate
And then win the by-election

Labour whips usually control when the writ is moved, and the party could theoretically slow-walk the process, delay the by-election, or complicate Burnham’s route back.

How long have previous by-elections taken?