Britain’s Conservative Party suffered sweeping setbacks on Friday in local elections that are viewed as a barometer for how the party will perform in a coming general election and a key test for the embattled prime minister, Rishi Sunak.
With more than three-quarters of the results announced by Friday evening, the Conservatives were on course for one of their worst performances in a set of local elections since the 1990s. The party has lost more than 350 seats so far, including six in Hartlepool, a town in northeast England emblematic of the expanded political territory it had claimed since Brexit, and is now losing to a resurgent Labour Party.
The Conservatives did score one notable victory in a closely watched race for mayor of Tees Valley, also in northeast England, where the Tory incumbent, Ben Houchen, held on, eking out a reduced majority.
Almost everywhere else, however, the picture was bleak for the Conservatives, who have trailed the opposition Labour Party by double digits in national polls for 18 months and face the prospect of a landslide defeat in a general election.
“It appears to be the worst local elections for the Conservatives since the final years of the era of Margaret Thatcher and John Major,” said Robert Hayward, a polling expert and Conservative member of the House of Lords, referring to the period before Tony Blair’s emphatic general election victory in 1997.
In Blackpool South, a seaside district, Labour won a special election for a parliamentary seat in a huge swing of votes away from the Conservatives, who placed a distant second, narrowly in front of Reform U.K., a small right-wing party. The previous Tory member of Parliament, Scott Benton, resigned in March after being embroiled in a lobbying scandal.
Labour’s leader, Keir Starmer, described the outcome in that district as a “seismic win” and the most important result of the day. “This is the one contest where voters had the chance to send a message to Rishi Sunak’s Conservatives directly,” Mr. Starmer said, “and that message is an overwhelming vote for change.”
Mr. Sunak conceded that the loss of so many Conservative council seats was “disappointing,” but applauded the victory in Tees Valley. Labour “threw absolutely everything” at that election, he said, but failed.
Still, the setbacks extended into the prime minister’s own backyard: Labour won the mayoral race for York and North Yorkshire, which includes Richmond, the area represented by Mr. Sunak in Parliament.
Voters went to the polls on Thursday in 107 towns and cities in England to elect council members, as well as 11 mayors, including in London, where results will be announced on Saturday.
With Mr. Sunak’s party badly divided and time running out before he must call an election by next January, the results were being closely scrutinized. While analysts expected the Conservatives to lose a significant number of seats, allies of Mr. Sunak feared that a worse-than-expected outcome could galvanize his critics in the party to try to topple him and install another leader.
The prime minister’s allies hope that some conspicuous victories — particularly in two regional mayoral races — will reassure Tory lawmakers, stabilize his shaky leadership and end speculation about whether he will lead the party into the general election, expected in the fall.
Mr. Houchen’s victory in Tees Valley eased some of the pressure on Mr. Sunak. But even that glimmer of good news was double-edged because Mr. Houchen had campaigned mainly on his own brand rather than that of his party, and his majority dropped to around 53 percent from almost 73 percent of the vote in 2021.
The result of the other key mayoral contest, in the West Midlands, is not expected until Saturday, and the Conservative candidate there, Andy Street, also distanced himself from the party during the campaign.
Even if the Conservatives win both races, they are braced for the loss of at least 400 council seats out of the 985 they are defending. Many of these elections are in towns and cities that were traditionally dominated by the Labour Party but that switched to the Conservatives in the years after the 2016 Brexit referendum.
To make matters more difficult, the last time many of these races were fought, in 2021, Mr. Sunak’s Conservatives were enjoying a period of popularity because of a robust rollout of a coronavirus vaccine by one of his predecessors, Boris Johnson. That means the Tories could have a long way to fall back.
In addition to Hartlepool, Labour won control of councils in Redditch, Thurrock, Milton Keynes and Rushmoor in Hampshire, although it had a setback in Oldham, where it remains the biggest party but lost overall control of the council after some of the seats fell to independents.
That reflected internal dissent over Labour’s stance on the Israel-Hamas war, analysts said, particularly among Muslim voters, many of whom say the party’s leaders should be more vocal in criticizing Israel’s military action in Gaza.
For Mr. Starmer, the election is a chance to show that he is on track to become Britain’s next prime minister, as current polling suggests. Despite his party’s strong numbers, few voters seem enthusiastic about Mr. Starmer, who is viewed as a competent but not especially charismatic politician.
John Curtice, one of Britain’s leading polling experts, estimated that if the local results were replicated across the country, Labour would win 34 percent of the vote — a nine percentage point lead over the Conservatives, who would have 25 percent. That would be a huge drop in support for the Tories since the last general election.
Voters in London will have to wait until Saturday to discover if the mayor, Sadiq Khan, has won a third term, which would be the first for a London mayor since the post was created in 2000. Mr. Khan’s defeat by his Tory opponent, Susan Hall, would be a big surprise, as the British capital leans left politically. But assuming he wins, the margin of victory would be watched for signs of dimming popularity.
The overriding challenge is for the Conservatives, however. The loss of seats could demoralize the party’s faithful and panic Tory lawmakers, who fear that they will be tossed out of Parliament in the general election.
For Mr. Sunak, the polls are now so dire that some see a new leader as the only possible way to fend off a ruinous defeat in the general election. In January, a former cabinet minister, Simon Clarke, called on the prime minister to resign, but that failed to foment a bigger rebellion.
Since they were last elected in a landslide in 2019, the Conservatives have already ousted two leaders, Mr. Johnson and Liz Truss. Toppling a third would be risky, since there is no obvious replacement guaranteed to be more successful than Mr. Sunak, and by Friday afternoon, there were no fresh calls from Conservative lawmakers for the prime minister to quit.
Mr. Johnson offered a reminder of his disorganized leadership style on Thursday, when he turned up at a polling station without photo identification — a requirement that his own government introduced in 2022 — and was turned away (he returned later with the proper ID).
