Labour will stage a Commons vote to try to force out Boris Johnson out of No 10 immediately, if he tries to stay on as a caretaker.
Keir Starmer urged Conservative MPs to “get rid of him” now – rather than serve a two-month interim period, while a successor is elected, saying: ”He can’t cling on in this way.”
“If they don’t get rid of him, Labour will step up in the national interest and bring a vote of no confidence because we can’t go on with this prime minister clinging on for months and months to come,” the Labour leader said.
Asked if Tory MPs would “unite” behind the man in No 10, Sir Keir argued: “I don’t think anything will unite this particular Conservative party.”
He spoke out as Mr Johnson filled several vacant cabinet posts and apparently made plans for an afternoon meeting – even before he has formally announced his resignation.
The moves are a clear signal of his intention to use the next two months to try to shape his legacy by making important policy decisions – flouting yet another part of the UK constitution.
Worried senior Tories are lining up to demand he be removed immediately, with Dominic Raab, the deputy prime minister, serving as the caretaker.
But there is no obvious mechanism to force Mr Johnson out before a successor is found, if he refuses to go willingly.
Sir Keir said Mr Johnson had “inflicted lies, fraud and chaos in the country”, adding: “He’s unfit to be prime minister. That’s been blindingly obvious for a very, very long time.”
Earlier, George Freeman, who quit as science minister, tweeted: “Boris Johnson needs to hand in the seals of office, apologise to Her Majesty & advise her to call for a Caretaker Prime Minister To take over today”.
Nick Gibb, the former schools minister, said: “As well as resigning as Party leader the PM must resign his office. After losing so many ministers, he has lost the trust and authority required to continue.”
Dominic Cummings, Mr Johnson’s former aide and now bitter enemy, was blunter: tweeting: “Evict TODAY or he’ll cause CARNAGE.
“Even now he’s playing for time & will try to stay No ‘dignity’, no ‘interim while leadership contest’. Raab shd be interim PM by evening.”
And Ruth Davidson, the former Tory leader in Scotland, warned: “There’s no way he can stay on until October. It’s arrant nonsense to think he can. Someone needs to grip this.”
Other prime ministers have used a caretaker period to shape their legacy, notably Theresa May who passed the landmark legislation committing the UK to net zero carbon emissions.
Mr Johnson will be keen to do the same – and has the added motivation of needing to stay in Downing Street for another 28 days to outlast his predecessor.
Extraordinarily, Mr Johnson is thought to still be planning a big economic speech in the next few weeks, to shape momentous decisions on future Treasury policy – including, possibly, tax cuts.