Labour have said the Tories’ dire local election results marked a “clear rejection” of Rishi Sunak as they became the largest party of local government since 2002.
Sir Keir Starmer was celebrating wins in key battlegrounds as an indication his party was on course to win the next general election.
The prime minister was under pressure as Conservative losses neared the 1,000 worst-case prediction senior Tories had floated to manage expectations ahead of the poll.
With 229 results declared out of 230 in the England council elections, the Conservatives had lost 960 seats, according to the PA news agency.
Broadcasters Sky and the BBC said the party had lost more than 1,000 but PA’s election data does not count those who defected or left the party since being elected as Tories.
Labour gained 635, PA said, while the Lib Dems gained 416 and the Greens 200.
Ukip lost all its six seats, and Reform UK lost eight of its 16 seats, with more than 360 independents and councillors losing their seats.
The Greens made a record number of gains, the party’s best-ever result at a local election, and gained control of their first English local authority, in Mid-Suffolk.
The Conservatives lost control of 48 councils, with Labour gaining 22, the Lib Dems 12 and the Greens one, and there were an additional 16 hung councils.
Full complete results will be revealed on Tuesday, when two final seats are declared after counting resumes at Redcar & Cleveland council.
Sir Keir’s party was projected to have won a nine-point lead over the Conservatives if all of Britain had gone to the polls, as the Tories slid backwards.
Vote share analysis by the BBC put Labour on 35%, the Tories on 26% and the Lib Dems on 20%. That was the same for Labour last year, but the Conservatives had sunk from 30%.
The broadcaster said the projection would make Labour by far the largest party but it would fall 14 seats of an outright majority, though voters are likely to act differently in a general election.
Sir Keir said the “fantastic” results combined with a hoped-for recovery in Scotland would give him a majority in Westminster after a national poll.
“Make no mistake, we are on course for a Labour majority at the next general election,” the Labour leader told activists in Medway, which his party will run for the first time since 1998.
A Labour spokesperson said: “The British public has sent a clear rejection of a prime minister who never had a mandate to begin with.”
Lib Dem leader Sir Ed Davey said: “It’s little wonder Rishi Sunak is running scared of a general election, because he knows we are set to take swathes of seats across the Conservative Party’s former heartlands.”
Sunak conceded the results were “disappointing”, but said he was “not detecting any massive groundswell of movement towards the Labour Party or excitement for its agenda”.
The contests were the first to be held under new rules requiring voters to carry photographic ID and the elections watchdog said some people were turned away from polling stations.
With Sophie Wingate and Sam Blewett, PA Political Staff