Boris Johnson’s attempts to cling to power in the past 48 hours came to an end on Thursday as he quit as Tory leader, saying he would stay on until the party elected a new head.
But senior party members and opposition parties have urged the Prime Minister to leave as soon as possible.
The First Minister stressed that he would not simply act as a “caretaker Prime Minister”.
Speaking to the BBC, Nicola Sturgeon said: “Given Boris Johnson has so clearly lost the confidence of the UK – and I think that has been the case for some time according to, not just opinion polls but recent by-elections – he has also lost the confidence of the House of Commons and his own party, it is just an unsustainable proposition to say that he will continue to inhabit Number 10 for three to four months.
“Particularly given the character and personality of Boris Johnson.
“I’m not sure that anybody can look at Boris Johnson and conclude that he is capable of genuinely behaving as a caretaker prime minister.
“He will want to do things and in the process of that undoubtedly cause more chaos than he has already.”
She added: “The interests of people from all parts of the UK surely must be to bring this farce to an end, without any further delay.”
The First Minister added that there would be a “overwhelming and very widespread sense of relief” that the Prime Minister is leaving office.
Scotland, Ms Sturgeon said, would now see “one Prime Minister that we did not vote for replaced by yet another Prime Minister that we did not vote for and would not vote for given the chance”.
“For Scotland, the Westminster system doesn’t represent our best interests and that is why we don’t just need a change of Prime Minister or a wider changing of the guard at Westminster, I think Scotland needs a permanent alternative to Westminster, which is why the independence choice is so necessary.”
The First Minister added that the Prime Minister had always been “manifestly unfit” for office, telling STV News he had been “lurching from crisis to crisis” in previous days.
Scottish Tory leader Douglas Ross, who had previously voted against the Prime Minister in last month’s confidence vote, said the Prime Minster had “finally made the right decision to resign”.
Mr Ross later told STV: “We don’t yet know the timetable from the 1922 Committee for electing a new leader, but if it is a significant amount of time, I think the best option would be for an interim Prime Minister to take over.
“Given the events of the last 36 to 48 hours, it would be very difficult for the Prime Minister to continue.
“There are so many vacancies within Government at the moment, I think that would be very problematic.”
Mr Ross also ruled himself out of running for the top job, and tipped Dominic Raab to take over on an interim basis until a new leader could be chosen by Tory MPs.
Scottish Secretary Alister Jack, following Mr Johnson’s Downing Street speech where he announced his departure, said he was “sad” to see the Prime Minister stand down.
“He has achieved a huge amount in office, including delivering Brexit, supporting the country through Covid, and leading the international response to Russia’s invasion of Ukraine. Most importantly, he has worked tirelessly to strengthen the Union.
“Boris is a good friend, as well as the leader of my party, and I wish him well for the future.
“I know that the next leader of the Conservative Party will build on Boris Johnson’s many achievements. I look forward to the party electing a leader who will unite us, and get on with the business of delivering for people throughout the United Kingdom.”
While one of Mr Ross’ predecessors – Baroness Ruth Davidson – said it was “arrant nonsense” the Prime Minister was going to stay on until a new leader was elected.
“There’s no way he can stay on until October,” she said.
“It’s arrant nonsense to think he can. Someone needs to grip this.”
Scottish Labour leader Anas Sarwar said whoever replaces the Prime Minister will have been “complicit” in his administration.
“The entire country will breathe a sigh of relief that Boris Johnson is going,” he said on Twitter.
“But, let’s not forget that whoever replaces him is complicit. We don’t just need a change at the top, we need a change of Government.”
Mr Sarwar later described the Prime Minister as a “cheat, a charlatan, a man devoid of any principles or any values”.
Scottish Government minister, and Scottish Green co-leader, Patrick Harvie, said it was a “huge relief” that the Prime Minister would be stepping down, although “suggestions he can remain in office until October are ridiculous”.