Confidence in U.K. Prime Minister Keir Starmer continues to erode, casting the future of his 18-month-old government in doubt amid the expanding fallout from the release of millions of files related to convicted sex offender Jeffrey Epstein. 

The latest blow to Starmer was a stunning loss Friday in a parliamentary vote in Manchester, in which his Labour Party slid to a weak third, hemorrhaging votes on both the right and left. 

Starmer was already politically hobbled by the arrest this week of Peter Mandelson, the prime minister’s hand-picked ambassador to the United States. But even before that, voters were souring on Starmer, who was the first left-of-center head of government in the U.K. after nearly 15 years of conservative rule. 

In a weekly national tracking poll from before Mandelson’s arrest, the Labour Party had less support than the nationalist Reform UK party, with Reform UK at 28% and Labour at 22%. The Conservative Party, which had provided the five prime ministers that preceded Starmer, was a close third, with 20% support. Labour had a comfortable lead over the two right-of-center parties as recently as December.

Other polls told a similar story: Ipsos’ Political Monitor from late January showed that just 15% of voters were “satisfied” with Starmer’s performance, compared to 77% “dissatisfied,” producing a net approval rating of minus 62 points, a record for the prime minister’s tenure. 

YouGov showed his net approval at minus 57 in February, while a More in Common poll this month pegged it at minus 43. 

Mandelson’s arrest has only complicated matters for Starmer. While there is still no public information indicating the 72-year-old former ambassador engaged in sexual misdeeds, he was arrested this week on “suspicion of misconduct in public office,” stemming from indications he might have provided Epstein with secret government information. Mandelson denied wrongdoing, according to police statements.

The charges against Mandelson, a long-time Labour Party powerbroker, were similar to those against Andrew Mountbatten-Windsor a week earlier. Mountbatten-Windsor is the former Prince Andrew and the younger brother of British King Charles III. But he was stripped of his royal titles as a consequence of his connection to Epstein. 

The developments put Starmer in real political danger. Labour’s weak performance in the parliamentary elections in the Manchester seat of Gorton and Denton – a one-time Labour stronghold – was seen as having a symbolic impact on Starmer’s government. 

Also in the parliamentary vote in Manchester, won by the environmentalist Green Party to Labour’s left and the Reform UK Party on the right, Labour barely totaled half the votes it garnered in 2024. 

Still, Starmer said he was undeterred by the results. 

“I will not stop fighting the extremes of politics,” the prime minister said. 

But analysts said the swing in votes was significant. 

“What we are seeing is more than typical mid-term blues,” polling expert Rob Ford of the University of Manchester said. “These are signs of an existential crisis.”

In the Manchester vote, Starmer also staked his personal authority on Labour winning the seat by blocking one of his rivals, the popular Manchester mayor Andy Burnham, and by visiting the constituency earlier this week, although British leaders normally avoid campaigning in local areas if they risk losing.

However, Starmer’s allies have not abandoned their leader. While they admit the Mandelson appointment was a poor decision, they say the prime minister is being judged through what they called “a scandal driven lens” that does not have a direct relation to Starmer himself. 

They have crafted a plan that involves the release of all the documents related to the nomination and vetting of Mandelson in hopes that will allow voters to move on from the topic. 

Labour officials say they want to turn attention away from perceptions of Starmer’s integrity and competence back to policy, which they see as a winning issue. 

Policy proposals include creating a National Wealth Fund, tightening border security, reducing waiting times at state hospitals, and improving workers’ rights.