Keir Starmer has ruled out even an informal post-election deal with Liberal Democrats, following a similar pledge about the Scottish National party, as Labour seeks to close down Conservative accusations about a possible coalition. Interviewed by Bloomberg, the Labour leader said his party would not go into coalition with “anyone”, including the Lib Dems, who under current polling could win a series of Conservative-held seats in the next election. Asked whether this commitment also covered a more informal deal such as confidence and supply, under which Lib Dems could commit to supporting a minority Labour government without a formal coalition, Starmer replied: “I’m ruling out any arrangement.” In a speech earlier this month, Starmer confirmed that Labour would never do a formal or informal deal with the SNP, as he sought to tackle future Conservative attacks about a “coalition of chaos”. Ahead of the 2015 election, David Cameron’s Conservatives focused heavily on this idea, in which Labour under Ed Miliband supposedly would be reliant on the SNP. One of the most resonant advertising images of the campaign was a Tory poster showing Miliband in the breast pocket of Alex Salmond, the then SNP leader. Downing Street is widely predicted to be considering a similar message before the next election, with polls showing the Conservatives would be defeated but with Labour most likely falling short of a majority. Starmer was scathing about this likely tactic, telling Bloomberg: “If people want a definition of chaos in politics, look at the government we’ve got at the moment.” Elsewhere in the interview, Starmer accused Boris Johnson of having “basically checked out”, while reiterating his criticism of the “arms race” about tax cuts among the candidates to replace him. “The single biggest problem of the last 12 years has been low growth: it’s why we’ve got such an acute cost of living crisis, why we have got inflation that is so high,” he said. “Any sense that the Conservative party is the party of the economy has just been blown out of the water. If you look at the leadership race that’s going on, it’s absolutely fantasy economics.” Johnson has seemed a sometimes peripheral figure since stepping down as Conservative leader 11 days ago, setting in train a succession process under which he will be replaced as prime minister in early September. He has not chaired any of a series of recent meetings of the government’s Cobra emergency committee leading the response to the unprecedented red weather alert for heat across England on Monday and Tuesday. Johnson spent the weekend at the prime ministerial country retreat of Chequers, where he held a party for colleagues and staff, and visited the Farnborough airshow on Monday. Starmer said: “We’ve got a prime minister who has basically checked out, he’s not doing anything.”