The popularity of Scotland’s First Minister has plummeted among his party’s voters a new poll suggests.

Research body Norstat – formerly Panelbase – spoke to 1,086 Scots for the Sunday Times between April 9 and 12.

Humza Yousaf’s net popularity score fell to -7% among the 389 people who voted SNP at the 2019 general election in the study – compared to a positive 14% approval rating in January – with some 29% saying the First Minister was doing a good job, while 36% felt the opposite.

Scottish Conservative leader Douglas Ross
Scottish Conservative leader Douglas Ross’s net approval rating dropped 10 points to -38% (Andrew Milligan/PA)

Meanwhile, with the general public, the First Minister’s net approval dropped close to that of his Conservative rivals.

He shed 15 percentage points, falling to -32%, while Prime Minister Rishi Sunak increased his rating by 10 points, but remained on -35%, and Scottish Tory leader Douglas Ross went the opposite way from the Prime Minister, dropping 10 points to -38%.

The leaders of Labour north and south of the border also saw a substantial dip in popularity, but remained well above Mr Yousaf and the two Tory leaders.

Sir Keir Starmer dropped 13 points to -25%, while Anas Sarwar’s popularity fell by 14 points to -17%.

In Westminster voting intention north of the border, Labour and the SNP were neck-and-neck, both on 32%, with Mr Sarwar’s party shedding four points since the last poll, and Mr Yousaf’s losing one point.

The SNP figure was the lowest recorded by Norstat since the 2014 referendum and polling expert Professor Sir John Curtice projected such a result would see 18 MPs for the party after the next election – well below the majority target its has set itself in its pursuit of independence, while Labour would win 28 constituencies.

Backing for the Scottish Greens – who have promised to field at least 32 candidates at the next election – and the Alex Salmond-led Alba Party, Sir John said, would transform the SNP’s electoral fortunes.

The parties sit on 4% and 2% respectively, but that is enough to lose them key battlegrounds.

If those voters backed the SNP, the polling expert said, Mr Yousaf could be celebrating winning 31 seats at the next election, compared to Labour’s 16.

Scottish Labour deputy leader Dame Jackie Baillie said: “After years of division and decline under both the SNP and the Tories, Scotland is ready for change.

“Scottish Labour is working around the clock to earn voters’ trust and demonstrate that we can deliver the change Scotland needs – including lower bills, higher wages, renewed public services and a stronger economy.”

Scottish Tory chairman Craig Hoy said: “Even SNP voters think that Humza Yousaf is doing a shoddy job as First Minister.

“It is clear that voters are growing tired of the SNP’s constant infighting and obsession with independence.”

SNP Depute Leader Keith Brown said: “After over a decade of catastrophic decline, the Tories and Keir Starmer’s Labour Party are offering nothing more than the same old right-wing disastrous policies that got us into this mess – only the SNP is giving people the chance to vote for a better future.

“The SNP will continue to make the case for a brighter future for Scotland and its people while the Westminster parties plod on trying to sell voters Westminster’s broken Brexit Britain.

“At the general election, people have a choice between a broken Brexit Britain and the failed status quo of an out-of-touch Westminster system – or voting for a more fairer, more prosperous independent Scotland by electing SNP MPs who will champion Scottish interests.”