If Keir Starmer resigned as Labour leader and prime minister, there is no automatic single “replacement” who simply takes over permanently – instead, a leadership contest would be triggered inside the Labour Party, and the winner of that contest would then become prime minister.

What happens immediately if he quits?

In the first instance, Labour would need an interim or acting leader to keep the government functioning while a contest is run.

  • The party’s National Executive Committee (NEC) and parliamentary leadership would agree interim arrangements, typically choosing a senior figure (for example the deputy or another senior cabinet member) to serve as acting leader.
  • The monarch would keep Starmer as prime minister until a successor is clear, or invite the new Labour leader to form a government once elected.
  • Day‑to‑day governing continues, but major political decisions might be softened or delayed while the party is in flux.

The precise name of the acting leader would depend on political deals and internal party rules at the moment he resigns; it isn’t fixed in advance in law.

How is the next leader chosen?

Labour has a formal leadership election process, similar to how Starmer himself was elected.

  1. Nominations
    • Any MP who wants to run must get support from 20% of Labour MPs.
    • With Labour currently around 404 MPs, that’s 81 backers needed to get on the ballot.
  1. Shortlisting
    • Once the nomination threshold is met, the approved candidates go forward to the wider party.
    • Affiliates (like trade unions) and local parties can endorse candidates, shaping the race.
  1. Members’ vote
    • Labour members, affiliated supporters and registered supporters then vote.
    • The winner becomes party leader and, because Labour has a Commons majority, would be invited by the King to be prime minister.

So, politically the question is less “who automatically takes over?” and more “who can get 81 MPs and then win the party membership?”

Who are the main names being talked about?

Commentary and betting markets in early 2026 mention a cluster of frontrunners and “plot” candidates rather than one obvious heir.

Commonly mentioned:

  • Angela Rayner – Former deputy prime minister and long‑time grassroots favourite
    • Strong support from parts of the trade union movement and Labour’s left‑leaning base.
* Her past tax affairs controversy makes some MPs nervous, but she’s still seen as a serious contender or king‑maker.
  • Wes Streeting – Health secretary
    • Frequently cited as a leadership prospect, with a high media profile and backing from parts of the party’s right and centre.
* Not universally loved among members but viewed as electorally minded and media‑savvy.
  • Shabana Mahmood – Home secretary
    • Tipped as a leading “continuity Starmer” candidate, praised by figures like Tony Blair.
* Seen as on the party’s right; her chances partly depend on whether Streeting also runs, as they fish in similar waters.
  • Andy Burnham – Mayor of Greater Manchester
    • Long‑running “threat” figure from outside Westminster, with two previous leadership bids behind him.
* Would likely need to enter Parliament first (e.g., via a by‑election) before realistically becoming prime minister.
  • Ed Miliband – Environment secretary, former Labour leader
    • Surprisingly mentioned in some recent commentary as a possible “safe pair of hands” with experience leading the party.

Other figures, such as Scottish Labour leader Anas Sarwar, are sometimes floated as influential voices or longer‑shot contenders, but they are not seen as the most immediate successors in Westminster speculation.

Quick HTML table of main touted successors

html

<table>
  <tr>
    <th>Potential successor</th>
    <th>Current/Recent role</th>
    <th>Key strengths</th>
    <th>Main challenges</th>
  </tr>
  <tr>
    <td>Angela Rayner</td>
    <td>Former Deputy PM, senior Labour figure [web:1][web:7]</td>
    <td>Popular with working‑class voters, strong union and grassroots ties [web:1][web:7]</td>
    <td>Previous tax‑affairs scandal, polarising with some MPs [web:1][web:7]</td>
  </tr>
  <tr>
    <td>Wes Streeting</td>
    <td>Health Secretary [web:3][web:4]</td>
    <td>High media profile, seen as electorally focused and competent [web:3][web:4]</td>
    <td>Not the favourite of the wider membership, associated with party’s right [web:3][web:4]</td>
  </tr>
  <tr>
    <td>Shabana Mahmood</td>
    <td>Home Secretary [web:7]</td>
    <td>Backed by senior figures like Tony Blair, rising profile [web:7]</td>
    <td>Competes for similar base as Streeting, also seen on right of party [web:7]</td>
  </tr>
  <tr>
    <td>Andy Burnham</td>
    <td>Mayor of Greater Manchester [web:7]</td>
    <td>Popular “outside Westminster” figure, long seen as leadership material [web:6][web:7]</td>
    <td>Not currently an MP, would need a route into Parliament [web:6][web:7]</td>
  </tr>
  <tr>
    <td>Ed Miliband</td>
    <td>Environment Secretary, former Labour leader [web:1]</td>
    <td>Experience as past leader, strong support among some Labour members [web:1]</td>
    <td>Memories of 2015 defeat, may not fit “fresh start” mood [web:1]</td>
  </tr>
</table>

How forums and commentators are talking about it

Political forums and commentary treat “if Keir Starmer resigns who takes over” as an open power‑struggle question, not a fixed succession.

Common themes you’ll see in discussions:

  • Continuity vs change:
    • Some want a continuity candidate to protect Labour’s majority and present stability.
    • Others argue for a more radical or charismatic figure to “reset” after the Mandelson–Epstein backlash.
  • Members vs MPs:
    • MPs often prioritise who looks “prime‑ministerial” on TV.
    • Members might favour someone who feels closer to the party’s values and grassroots.
  • Timing and stability:
    • Many posts point out that forcing Starmer out mid‑term risks making Labour look divided, which is why some senior figures still publicly tell colleagues he should stay.

As one typical take paraphrased in commentary puts it:

If Starmer goes, it’s a full‑on Labour leadership war, not a coronation – Rayner, Streeting, Mahmood, Burnham and others will all be testing the waters.

Bottom note

Information gathered from public forums or data available on the internet and portrayed here.