Scottish voters' "loathing" for Boris Johnson is the main factor behind the recent surge in support for independence, according to an extensive new analysis.
A poll by JL Partners conducted last month found 56 per cent support for separation and 44 per cent opposition, a result in line with a series of similar surveys.
But it found that the most persuasive argument in favour of independence was "Boris Johnson is not the leader I want to have for my country", a sentiment that 79 per cent of swing voters agreed with.
Among the other factors driving the increase in support for separation were Brexit, the UK Government's handling of the pandemic and a desire to settle the independence question once and for all.
The poll also showed that Nicola Sturgeon is on course for a landslide win in next May's Holyrood election, with 58 per cent support for the SNP in the constituency vote compared to only 19 per cent for the Tories and 13 per cent for Labour.
She has said she will use the contest to seek a mandate for another independence referendum, placing huge pressure on the Prime Minister to hand her the powers to stage another vote.
He has pledged to hold Ms Sturgeon to her promise before the 2014 referendum, which the Unionist side won by 55 per cent to 45 per cent, that it was a "once-in-a-generation" vote.
But the poll was published amid claims of panicking in Downing Street over the surge, with some Tories believing that refusing a mandate won in a democratic election would play into Ms Sturgeon's hands.
Jamie Johnson, who leads JL Partners and was Theresa May's pollster, said that focus groups of Scottish voters showed that Mr Johnson was "loathed" in a way that she or David Cameron were not.
He told the POLITICO website: "It is hard not to look at these figures and assume the Union is doomed. It is certainly the gravest situation the Unionist cause has found itself in in recent history."
The Prime Minister accepted his unpopularity contributed to the SNP's general election landslide in Scotland last December, and the poll suggests his handling of the pandemic has further damaged his ratings.
It found that 84 percent of swing voters think the UK Government handled the situation badly, compared to 74 percent who say the Scottish Government handled it well. This is despite Scotland, along with England and Wales, having one of the highest excess death rates in Europe.
The most persuasive argument for staying in the UK among swing voters was “an independent Scotland is a step into the unknown”, a statement 69 per cent agreed with.
The poll found Chancellor Rishi Sunak and Ruth Davidson, the former Scottish Tory leader, were the most popular Conservative figures north of the Border. Mr Sunak's +30 net rating among swing voters was even higher than the Queen's.
If there was another referendum, James Johnson said "No 10 should lock away Boris, and put up Rishi and Ruth.”
Among senior Labour figures, Sir Keir Starmer, Gordon Brown and Alistair Darling were viewed the most favourably among undecided voters.
Keith Brown, the SNP's depute leader, said: "“People in Scotland believe they have the right to take their own decisions rather than being subject to Westminster governments, led by the likes of Boris Johnson, that we don’t vote for.
“With consecutive polls putting support for independence above 50 per cent, it’s clear that majority support for independence is no longer a trend, but now the settled will of the people of Scotland."
A Scottish Tory spokesman said: "In the middle of a global pandemic, the last thing Scotland needs is a second divisive independence referendum.
“We are appalled that several SNP ministers, including their constitution minister Mike Russell, have suggested holding another referendum next year.
“The Scottish Conservatives led by Douglas Ross are the only party with the strength to stand up to the SNP and move Scotland on from the divisions of the past.”