Labor has described Prime Minister Malcolm Turnbull as "unhinged" for claiming that Bill Shorten is the most left-wing ALP leader in decades.
Turnbull launched a scathing attack on Shorten at a Liberal Party meeting in Adelaide on Saturday, telling party faithful that only the coalition could run South Australia effectively.
In the address, Turnbull said the current Labor Party was not the same institution as that led by former prime ministers Bob Hawke and Paul Keating.
"This is the most dangerous left wing leader of the Labor Party we have seen in generations," Turnbull told the event.
Responding to the comments, shadow attorney-general Mark Dreyfus said they showed how weak Turnbull had become as prime minister.
"I saw that yesterday, it's unhinged actually," Dreyfus told ABC television on Sunday.
"It is an indication of how desperate this weak prime minister is that he feels last week he should attack Bill Shorten personally for being too close to business, and on Saturday in Adelaide he thinks he's going to attack him for being left-wing.
"It's not left-wing to be concerned about inequality in Australia. It's actually the right thing any social democratic party would be concerned about."
Dreyfus said Turnbull's time would be better spent focusing on policies.
"I think most Australians are desperate to have proper leadership from their Prime Minister, not this sort of personal abuse."