Boris Johnson’s leadership is facing fresh peril after senior Conservatives blamed him for losing swaths of the party’s southern heartlands to the Liberal Democrats and flagship London boroughs to Labour. In a punishing set of local elections for the Tories, the party lost about 400 council seats, ceding control of Westminster and Wandsworth in London to Labour for the first time since the 1970s, and plunging to its worst position in Scotland for a decade. Conservative MPs and council leaders questioned Johnson’s leadership, demanding action to tackle the cost of living crisis and rebuild trust in the wake of the Partygate scandal after a damaging series of losses across the “blue wall” in Somerset, Kent, Oxfordshire and Surrey. However, the scale of the Tory backlash was tempered by a mixed picture for Labour, which showed progress, but not enough yet to suggest a landslide for Keir Starmer in a general election. A BBC projection for a general election based on Friday’s results put Labour on 291 seats, the Conservatives on 253, the Lib Dems on 31 and others on 75. Labour had a very strong result in London and took some southern councils such as Worthing, Crawley and Southampton, gaining about 250 seats in total. It pushed the Tories out of control in their only council in Wales, Monmouthshire, and took over as the party with the second largest vote share in Scotland, where the SNP remained dominant. But in the north of England and the Midlands, Labour struggled to make gains in “red wall” areas it had lost at or since the 2019 election, despite a convincing win on the new Cumberland council. Conservative HQ was also buoyed by the news that Starmer is now being investigated over allegations of Covid rule-breaking at a Durham campaign event, muddying the waters over Johnson’s own fine for a lockdown gathering. Starmer said the results were a “big turning point” for his party. “From the depths of 2019, that general election, winning in the north, Cumberland, Southampton. We’ve changed Labour and now we’re seeing the results of that.” The Lib Dems also had a clearly successful election night in England, adding at least 189 seats. They took control of the new unitary authority in Somerset, previously a Tory stronghold, edged out the Conservatives in Portsmouth, and pushed them out of control in West Oxfordshire. The Greens also performed well, winning 81 seats – more than doubling their number of councillors – as voters also turned to independents and residents’ associations. The Lib Dem leader, Ed Davey, called the results “an almighty shockwave that will bring this Conservative government tumbling down”. He described the result in Somerset, where his party took 56 seats compared with 29 for the Tories, as a “political earthquake”, and said rural communities were fed up with being taken for granted. There were also dramatic results in Northern Ireland, where Sinn Féin looked set to get the largest share of the vote for the first time, as the Democratic Unionist party suffered in the aftermath of the Brexit agreement. As the results got progressively worse for the Tories throughout Friday, Johnson’s MPs considered whether the outcome was dire enough to justify another an attempt to oust him. Conservative critics of the prime minister said they would be ringing round over the weekend to see whether the scale of discontent was enough to defeat Johnson in a confidence vote. They would need 54 letters from Tory MPs to trigger a contest and 179 votes against the prime minister to oust him. Even if they decide to wait to see the conclusion of Partygate investigations before acting, a one-nation Tory MP said there would be a push to get Johnson to consider bringing in more figures from the centrist wing of the party, such as Jeremy Hunt and Greg Clark, in response to the resurgent threat from the Lib Dems. One minister in a blue wall seat said: “The prime minister can certainly see off any threats from the usual suspects, who have never supported him and simply seek to find opportunities to challenge him, damaging the whole party in the process. But the party chairman [and] CCHQ [Conservative campaign headquarters] really do need to get their heads around the battleground for the election being here in the south, not in the north, and it not all being about Labour, who are still not making sufficient inroads to form a majority government.” Robert Buckland, the former justice secretary, said that while voters did not blame ministers for the cost of living crisis, the government would be judged on its response. “The danger for the government is it will be perceived to not have done enough to feel the pain and ease people’s pain,” he said. Buckland said opposition attempts to paint the Tories as heartless were gaining some traction but would prove more damaging if their competence was also brought into doubt. “That is why I think the government cannot just look at these results and say, ‘Everything’s fine, we can carry on business as usual’. They are going to have to signal they understand and are going to offer more help.” The Wimbledon MP Stephen Hammond, who saw the Lib Dems take council seats at the Conservatives’ expense in his local borough of Merton, said: “That ought to be a clarion bell ringing in Downing Street to make sure we are concentrating on the cost of living.” Asked about Johnson’s future, he told the BBC: “I think he has to prove his integrity to the country.” Many grassroots Tories laid the blame at Johnson’s door for the loss of their seats. John Mallinson, the Conservative leader of Carlisle city council, told the BBC he had “lost some very good colleagues” in the Cumberland local election, and had found it “difficult to drag the debate back to local issues” while campaigning, because of Partygate and the cost of living crisis. He said: “I think it is not just Partygate, there is the integrity issue. Basically I just don’t feel people any longer have the confidence that the prime minister can be relied upon to tell the truth.” Asked if Conservative MPs should remove Johnson, he said: “That would be my preference, yes.” Labour dismissed the suggestion it was not making progress, pointing out that its vote share was up in key battleground seats when measured against its catastrophic performance at the 2019 general election. It said that on this basis it looked on course to win back up to 26 seats that voted leave in the EU referendum, including Carlisle, Great Grimsby and Workington.