Anas Sarwar has claimed Liz Truss is “more dangerous than Margaret Thatcher” and is “worse than Boris Johnson”.
The Scottish Labour leader made the remarks in his speech at the Labour Party conference in Liverpool.
Sarwar insisted that his party will win the next general election, with Keir Starmer installed as the UK’s next prime minister.
He also ruled out the prospect of any electoral deals with the SNP, as he criticised the record of the party in power at Holyrood.
“We were right to cheer the removal of Boris Johnson, who shamed the office of Prime Minister,” Sarwar told Labour delegates at the ACC in Liverpool.
“But Liz Truss is worse than Boris Johnson. He didn’t believe in anything apart from himself.
“Liz Truss is a right-wing, ideological Tory. She is more dangerous than Margaret Thatcher.
“Let’s be clear – this is a corrupt, lying, incompetent, failing, cheating, economically illiterate, morally bankrupt shower and the sooner we boot them out the better.”
The Scottish Labour leader suggested that the failings of the Conservatives had allowed the SNP to “double down on their campaign of division” rather than facing their own record in government.
He said: “The truth is that far from being the great defender of the UK, the Tories are a gift to those who want to break us apart.
“In Scotland, the Tories’ failings have allowed the SNP to double down on their campaign of division rather than face up to their own record of failure in Scotland.”
Sarwar pointed to the number of Scots on NHS waiting lists, children and young people waiting for mental health appointments, and the country having the highest drug deaths rate in Europe.
“After 15 years in power, the SNP have squandered every chance, broken promise after promise, and left Scotland worse off than when they came to power,” he said.
“Always someone else of something else to blame. Conference, you know what I know, there is nothing progressive about Scottish nationalism.
“It goes against the values of solidarity and social justice. It is an ideology based on what divides us, not what unites us.”
The Scottish Labour leader insisted that the “politics of division” helps the Conservatives and SNP win election, but not to change people’s lives.
“While our opponents thrive on division, we know that real change comes when you pull people together,” he said.
“But in Scotland and across the UK, our politics has lost sight of that. I hate to break it to Liz Truss and Nicola Sturgeon, whether you voted yes or no, whether you voted leave or remain, your bills are going up.
“For too long, we’ve been led by parties which want to entrench us into camps and convince us to dislike and distrust one another.”
He added: “The politics of division helps the Tories and the SNP win elections, not change people’s lives.”
Sarwar ruled out the prospect of Labour striking any deal with the SNP as he set out his party’s aim of beating the Conservatives at the next general election.
He said: “For more than a decade, the SNP and the Tories have stoked up bitterness, division and anger, creating a politics of us versus them.
“But conference, we know those days are numbered. The occupiers of Downing Street and Bute House know the clock is ticking.
“So let’s be prepared for what lies ahead. In the coming months and years, our opponents will get more desperate.
“Their tone more irrational, their attacks on us more unhinged. That is because they know what we know – the next electoral contest will not be a referendum, it will be a general election.
“And conference, Labour will win the next general election, and Scotland will delivered the seats to get us over the line.
“Scotland will elect Keir Starmer as its next prime minister because only Labour can replace the Tories and change lives for the better.”