LONDON — Britain’s Labour MPs are talking furtively about ousting their leader. There’s just one hurdle: they need to work out how.

Prime Minister Keir Starmer is facing renewed outrage in his party after he admitted knowing that Peter Mandelson continued his friendship with the convicted sex offender Jeffrey Epstein, but appointed him as ambassador to the U.S. anyway.

It’s the latest crisis for Starmer, whose personal popularity has tanked despite Labour winning in a 2024 landslide. Yet while MPs have anonymously thrown around potential challengers’ names for months, nothing has happened. They include former Deputy PM Angela Rayner, Health Secretary Wes Streeting, Home Secretary Shabana Mahmood, Defence Secretary John Healey and 2024-entry minister Al Carns. (All publicly insist they are loyal to Starmer.)

The upshot is that Starmer could remain in office for months or even years, even while his own MPs drift from his leadership.

The hurdles are mostly political, given local elections looming in May and there is no single heir apparent, but procedure is to blame too. Labour’s internal rules, which have changed since the last time a sitting leader was challenged in 2016, are notorious for being far more opaque than in the opposition Conservative Party.

Challengers need 80 fellow MPs to back them in order to trigger a contest, but the exact process is “concerningly vague” and “muddy,” one Labour official said.

They added: “Everyone is fumbling around in the dark, hoping that they get enough momentum that it’s overwhelming and carries them over the line.”

A second Labour official said: “I would assume that 95 percent of MPs don’t actually understand how this works, hence there are widespread fantasies about being able to have a coronation.” They added: “I’m reasonably confident that people just won’t get their shit together.”

So POLITICO is here to help. We spoke to four Labour officials with knowledge of the process to clarify exactly how a hypothetical challenge would unfold, if it ever happens. All were granted anonymity to discuss internal processes.

Step 1: Find 80 friends — in secret

It will kick off a mile and a half from Downing Street, in the office of a Labour Party official who is seldom seen in the public eye.

Any challenger or their supporters must write to General Secretary Hollie Ridley with the names of 81 MP backers, including the challenger themselves.

This can happen either by email or with signatures on paper delivered to the party’s London headquarters. “I assume they would walk in and dump 80 letters on Hollie’s desk,” said one of the four officials noted above.

It’s unclear whether challengers should send one message signed by 81 people, or 81 letters (some officials who spoke to POLITICO were unsure; others thought either would be fine).

Either way, this means plotters must sign up one fifth of their party to a coup … without their efforts leaking and fizzling out midway through. And backers must be ready to be named publicly hours later. Given the level of gossip among Labour MPs, good luck with that.

These are much higher hurdles than in Britain’s Conservative Party, whose MPs can submit no-confidence letters anonymously and don’t need to attach them to a named challenger.

Politics will probably overtake the process in the end.

The last leadership challenge, against left-winger Jeremy Corbyn in 2016, was plain for all to see before it reached the formal stages — because a wave of ministers resigned and MPs passed a symbolic no-confidence vote in his leadership.

Step 2: A pause — then a whirlwind 

There will be a short pause while Ridley seeks internal and legal advice before the 81 names are published — and Labour hits a thousand miles per hour.

The party will convene a meeting of the 10 officers of Labour’s ruling national executive committee (NEC), which will make recommendations on the timetable and procedure to the wider NEC to wave through.

Other MPs will be invited to nominate rival challengers. As the sitting prime minister, Starmer will have a place on the list automatically.

But they will have to act fast. During the contest to find Labour’s new deputy leader in the fall, formal MP nominations were only open for three days and the entire contest was over in eight weeks.

NEC officers are largely pro-Starmer — they include Starmer himself, though any candidate would be recused from discussions — and were the same people who blocked Greater Manchester Mayor Andy Burnham from attempting to return to parliament in January.

They may have an interest in moving quickly, to avoid destabilizing the prime minister on the world stage or allowing a left-wing candidate to gain traction.

Step 3: Choose your fighters carefully

One piece of advice to warring MPs: Get it right first time.

The four officials all said that once MPs pick who to nominate, they are “locked in” and cannot transfer to another candidate unless their pick drops out of the race.

The full tally of MP nominations — with names — will be published daily on the Labour Party website, unlike the Tory system which uses a secret ballot.

Step 4: Get your rubber chicken out

Candidates who pass the 81 MP threshold will then go through to a second stage, where they spend weeks touring the country to persuade local parties and unions to back them.

They must win the support of 5 percent of Labour’s constituency parties, or at least three of the party’s formal “affiliate” bodies including two trade unions.

This is not always a formality, as Emily Thornberry — now chair of the Commons’ foreign affairs committee — discovered when she failed to reach the local party threshold when running against Starmer in 2020.

Two of the four officials noted above suggested that Wes Streeting — despite being widely seen as a frontrunner — could struggle during this stage, as many unions and constituency parties regard his politics as not left-wing enough. A third official said this was inaccurate, given there has been an exodus of left-wing members from the party.

Step 5: Go to the party

Whoever pulls through the initial stages — probably three candidates at the most — will go through to a final vote of Labour’s members.

The result is difficult to predict, as many of the most left-wing members who joined under Jeremy Corbyn in the late 2010s have exited the party. In October’s deputy leadership vote, Bridget Phillipson — who was widely painted as being aligned to Starmer — lost by only a small margin.

The winner will be Labour leader, and therefore prime minister. If Keir Starmer wins, he will stay in No. 10, secure until the next time a critic is strong enough politically to come for him. If a rival wins, Starmer will visit King Charles III to tender his resignation as PM.