How can a UK prime minister be ousted? From leadership challenges to confidence votes

Sir Keir Starmer is under immense pressure following the disastrous elections in England, Scotland, and Wales.

The prime minister is facing calls from his MPs to either go or set out a timeline for his departure after Labour lost more than 1,400 councillors in England, had its worst result in the Scottish Parliament since it was devolved in 1999, and lost control of the Senedd for the first time in the history of devolution.

He was also already in a dire position in his party following the appointment of Lord Peter Mandelson as ambassador to the US, and the fallout from the Epstein files revelations and the security vetting scandal.

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While no cabinet minister or mooted challenger has said they intend to launch a bid to oust the prime minister, dozens of Labour MPs are furious and are blaming Sir Keir's leadership.

One former minister, Catherine West, has said she will try to trigger a leadership contest if the cabinet does not act to replace Sir Keir by Monday.

We look at how a British prime minister can be ousted:

Leadership challenges

Each political party has their own rules around deposing a leader.

Labour Party

In the Labour Party, an MP has to inform the party's national executive committee (NEC) they intend to seek nominations for the leadership of the party.

The committee would then give a timetable for when that MP - and any others who want to contest the leadership - have to be nominated by at least 20% of Labour MPs (which would be 81 MPs at the moment, with the contender counting as one).

The challenger/challengers would have to be a member of parliament, ruling out someone like Greater Manchester Mayor Andy Burnham, who was denied the opportunity to return to Westminster by Sir Keir in a February by-election.

The leader being challenged would not have to secure any nominations and would automatically be on the ballot paper.

However, it is difficult to pull off a coup of this sort, given the high number of nominations required. While Gordon Brown faced open calls to go in 2008-9, the plotters could not get anyone serious to put their names forward as a challenger.

Realistically, the only way for a Labour prime minister to be forced to step down is if cabinet ministers resign from the government, declaring a loss of confidence in Sir Keir (more on that below).

Conservative Party

As we saw in the dying days of the Conservatives' time in office, a confidence vote can be triggered if a certain number of Tory MPs write to the chairman of the party's 1922 backbench committee requesting one.

It used to require 15% of the parliamentary party to call for a vote, but after the general election, it was raised to 30% to avoid the instability seen in the preceding years.

Theresa May and Boris Johnson faced such votes, and while they narrowly survived them, it damaged their authority and they did not last much longer in office (more on that below).

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Confidence vote

A core convention of the UK's constitution is that the government must command the confidence of the House of Commons. While governments don't have to consistently prove they "hold confidence", they are expected to resign or trigger a general election if they lose a confidence vote.

There are different ways in which this can come about.

The leader of the Opposition can table a vote of no confidence, which must explicitly state that the House has lost confidence in the government (rather than simply being critical of the leadership).

The last time this brought down an administration was in 1979, when James Callaghan's minority Labour government, plagued by a wave of strikes and high inflation, was defeated by 311 to 310. The knife-edge vote triggered a general election, which the Conservatives won under Margaret Thatcher - and Labour did not return to power for 18 years.

However, it is rare for governments to be defeated in confidence motions (before Callaghan, the last time this happened was Stanley Baldwin in 1924).

Often, under-fire prime ministers will bring about their own confidence vote, usually by declaring a key policy as a "matter of confidence".

This tactic was deployed by John Major in 1993, when, threatened with a general election, Eurosceptic Tory rebels got behind his controversial Maastricht Treaty on the foundation of the European Union.

Ministerial resignations

A tried-and-tested method of forcing out prime ministers is cabinet resignations.

Given the limited mechanisms for Labour MPs to privately declare a loss of confidence in a prime minister of their party, this is the only realistic way of putting enough pressure on them to step down without a direct challenge.

After Boris Johnson survived a no-confidence vote in July 2022, Conservative Party rules meant he was protected from another one for a year.

So, when he was embroiled in another scandal regarding the disgraced former deputy chief whip Chris Pincher, it sparked a mass revolt of cabinet ministers that made his position untenable.

Credibility damage

It doesn't always have to be ministerial resignations that tip prime ministers over the edge.

Liz Truss, who replaced Mr Johnson, resigned after just 44 days in office when her mini budget sparked such economic turmoil she had to rapidly row back on most of her measures.

This damaged her credibility to such an extent that she conceded she could not go on.

Theresa May also faced difficulty commanding authority. Her EU withdrawal deal was rejected three times by parliament as she failed to get hard-line Brexiteers on side, and she was forced to resign.

Tony Blair won an unprecedented three elections for Labour, but his standing suffered in the wake of the Iraq War. Following pressure from within the party to quit, and a plot to replace him with Gordon Brown, he announced an early departure date, resigning mid-way through his final term.

(c) Sky News 2026: How can a UK prime minister be ousted? From leadership challenges to confidence votes