Anas Sarwar will today say that Scottish Labour can beat the SNP in seats “across Scotland” at the next general election as he launches a scathing attack on Humza Yousaf's party accusing them of not putting the country first.

He will address Labour’s conference in Liverpool on Monday, where he will hail his party’s win in the Rutherglen and Hamilton West by-election.

Michael Shanks exceeded expectations and took 58% of the vote at the by-election count in South Lanarkshire last week.

While turnout was low, Labour achieved a swing of 20.4% from the SNP with Mr Shanks netting 17,845 votes - more than double the number polled by the SNP's Katy Loudon who got 8,399 votes.

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It was the first major electoral test for Humza Yousaf who succeeded Nicola Sturgeon as SNP leader and First Minister in March and followed the ousting of the previous SNP MP Margaret Ferrier in a recall petition in August after she broke Covid rules.

The dramatic Labour victory on Thursday led polling experts to believe that Labour could return to being the largest party north of the border, potentially helping to boost the chances of opening the door to Downing Street if there is a similar swing at the next general election expected before the end of 2024.

Mr Sarwar will say his SNP opponents have chosen to “blame the voters” for their loss.

"The result in Rutherglen and Hamilton West showed something I've long suspected, and that I imagine the SNP have long feared," he will tell delegates.

“The cracks in the foundations of the SNP are deeper and wider than they've ever recognised and while senior nationalists have lined up in TV studios to blame the voters - they have missed the point. 

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“Just like the Tories before them, they've made the mistake of thinking politics is a game.

"But I've got a message for them. Politics is about service - delivering for communities.

"It isn't about the same old constitutional fights and asking people to pay more for less. It isn't about failing to support our public services and trying to blame somebody else. Politics is about changing lives." 

He will add: "It is about delivering a future where everyone can live up to their potential. It is about serving the people of Scotland. That is what the SNP have forgotten. 

"It's that failure to stand up for Scotland, that failure to put country before party that has seen people turn their backs on them. 

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"Now no SNP MP can sit safely, taking their communities for granted as so many have.

"So I say to Humza Yousaf: this isn't about swings or the polls - this is about putting the people of Scotland first. 

"And because you won't do that - we can beat you across Scotland. Every community in Scotland now has the chance to choose change with Scottish Labour."

His accusation that the SNP have failed "to stand up for Scotland" and to put the country before party echoes the criticism made by former Scottish Government cabinet minister Fergus Ewing.

Mr Ewing was suspended for a week from the Holyrood SNP group earlier this month after he voted against the Scottish Government minister Lorna Slater in a no confidence motion back in June.

In a statement to journalists after his suspension Mr Ewing pointed to a series of policies pushed by the Greens which he believed were damaging to his constituents.

He said: "[The SNP] was never an ordinary political party because it was one which put Scotland first.

"In good conscience this is no longer the case and it has nothing to do with personalities or my antipathy towards the Green Party.

"It has to do with policies on the deposit return scheme, on fishing, on transport, tourism and small businesses, and on boiler replacement, which are deeply hostile to the interests of my constituency."

It is the second time in recent days that Mr Sarwar has referred to criticisms made by SNP figures towards their own party's leadership.

At First Minister's Questions last Thursday, as voters in Rutherglen and Hamilton West went to the polls, the Scottish Labour leader attacked Mr Yousaf's record on policing with reference to comments made by the narrowly defeated rival, SNP MSP Kate Forbes, in the party's leadership contest this spring.

Mr Sarwar told Holyrood: "When Humza Yousaf was Cabinet Secretary for Justice, the police were 'stretched to breaking point'. Those were the words of the SNP member whom some members sitting behind the First Minister wish they had elected as their leader."

Meanwhile, a poll published yesterday found that Mr Sarwar could become First Minister at the next Holyrood election in 2026 and lead Scottish Labour to power for the first time in two decades.

The survey predicted that his party is running almost neck and neck with the SNP, and is on course to be the largest party at Holyrood by a single seat.  

Although it suggested that it would be unable to form a majority, Scottish Labour could govern as a minority with support from the Lib Dems and Conservatives.  

Together the unionist block would command nine more seats than the SNP and Scottish Greens together, which would pave the way for bargaining and probably elevate Sarwar to Bute House. 

The Panelbase poll, for The Sunday Times, said the SNP have slipped a point to 35% in the constituency vote, while Scottish Labour remained on 32%.  

The Conservatives were up three points to 16%, the Lib Dems fell two points to 9%, while the Greens remained on 7%. 

The poll — which was conducted as Labour humbled the SNP in last week’s Rutherglen & Hamilton West by-election — suggested a growing unpopularity of Mr Yousaf, with one in six independence supporters now switching to Mr Sarwar’s party.