Jeremy Corbyn has told ITV News that Theresa May should resign as prime minister in the wake of the London Bridge terror attack.
The Labour leader said Mrs May should stand down for presiding over cuts in police numbers while home secretary.
Mr Corbyn told ITV News Correspondent Rachel Younger he backed similar calls by "very responsible people" who are "very worried" about her record.
Mrs May has come under opposition fire in the wake of Saturday's central London attack over the impact of the reduction in police numbers on British security.
Her tenure at the Home Office saw 20,000 fewer police officers on the country's streets as a result of government cuts despite vocal opposition from within the police service.
Asked if he backed calls for Mrs May's resignation, Mr Corbyn told ITV News: "Indeed I would."
Mr Corbyn said: "There have been calls made by many very responsible people on this who are very worried that she was at the Home Office for all this time, presided over these cuts in police numbers and that now we're saying that we're having a problem. Yes we do have a problem, we should never have cut the police numbers."
Asked if he was directly calling on Mrs May to resign, Mr Corbyn rolled back a little, saying: "We've got an election this Thursday and that's perhaps the best opportunity to deal with it."
The prime minister, addressing Tory supporters in Edinburgh, laughed off the prospect of her standing down three days before an election.
She said: "On Thursday the people of the UK have a very simple choice."
Mrs May earlier defended her record when asked about the cuts to police numbers.
Mrs May said: "The Commissioner of the Metropolitan Police has said that the Met is well resourced, and they are, and that they have very powerful counter-terrorism capabilities and they do.
"We have protected counter terrorism policing budgets, we have also provided funding for an increase in the number of armed police officers and since 2015 we have protected overall police budgets - and that's despite the fact that Jeremy Corbyn's Labour Party in the House of Commons suggested that police budgets could be cut.
"But it's also about the powers that we give to the police. We have given increased powers to the police to be able to deal with terrorists - powers which Jeremy Corbyn has boasted he has always opposed."
Culture secretary Karen Bradley earlier defended cuts to policing during a fiery debate on ITV's Good Morning Britain over Islamic extremism in the wake of the London Bridge attack.
Ms Bradley repeatedly avoided answering whether numbers of frontline police officers had been slashed since 2010.
She claimed the increase in counter-terrorism budgets meant there were more "specialist officers" on the streets.