The UK's top polling guru has warned that the SNP is at risk of losing a significant number of seats at the next general election after Labour recorded a thumping by-election win last night.
Michael Shanks took the Rutherglen and Hamilton West seat with 17,845 votes - more than double the number polled by the SNP's Katy Loudon after a swing of 20.4% from the SNP to Labour.
Professor Sir John Curtice said today that the SNP needs to make First Minister Humza Yousaf more popular if they are to stop Labour winning up to 24 seats in the forthcoming Westminster election.
The by-election was called after former SNP MP Margaret Ferrier was ousted by her constituents for breaking CV19 rules.
Labour leader Sir Keir Starmer said it was a "seismic" night and that people in Rutherglen and Hamilton West had sent "a clear message".
He added: "I have always said that winning back the trust of people in Scotland is essential. Tonight's victory is the culmination of three-and-a -half years of hard work and humility on that journey."
First electoral test for Humza Yousaf
Ms Loudon received 8,399 votes in the by-election, which was the first major electoral test for the SNP since Humza Yousaf succeeded Nicola Sturgeon as leader.
The first minister described it as a "disappointing" night for his party.
Mr Yousaf said the circumstances "were always very difficult for us" and that Labour had benefitted from a collapse in the Conservative vote.
"We lost this seat in 2017, and like 2019 we can win this seat back. However, we will reflect on what we have to do to regain the trust of the people of Rutherglen and Hamilton West," he said.
Prof Curtice, professor of politics at Strathclyde University, said it was a "remarkably good result" for Labour.
"It's well above the kinds of swings we've seen in the opinion polls in Scotland. The Labour vote is up to nearly 59%, that's 24 points."
Will we now see a Labour majority at Westminster?
Prof Curtice said wins by opposition parties on this scale are historically "on course for victory in a general election".
And he predicted that the SNP would have difficult time at the election if it remains on its current path.
He said: "Labour's claims that they could win 24 seats in Scotland certainly looks possible. I'm not going to say it is guaranteed, as the election could be 12 months away.
"If the SNP were hoping that the Labour challenge would disappear, it's now clear the SNP are going to have to figure out how they are going to improve their popularity among voters in Scotland.
"They have some continuing problems, not least the public division within the party to together with the fact that, frankly, Mr Yousaf just isn't as popular as his predecessor. Unless the party can address some of those problems, it is at risk of losing a significant number of its seats in the next general election.
"That doesn't just matter to Scotland. If Sir Keir Starmer can start winning seats in Scotland, his chances of getting an overall majority and avoiding an hung parliaments increase quite significantly."