Malcolm Turnbull insists Bill Shorten has been "caught out lying" over Labor's Medicare scare campaign.
The opposition leader, appearing on the ABC's 7.30 program, was not prepared to put hand on heart and repeat his claim the coalition had a plan to privatise Medicare.
Instead Mr Shorten told host Leigh Sales: "I can say to the people of Australia that this election and their vote on July 2 will determine the future of Medicare".
He also took the opportunity to argue the Liberal plan, which included a freeze on indexed Medicare rebates, was "scary".
The prime minister, campaigning in Launceston on Friday, seized on Mr Shorten's apparent change of language.
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"He was asked to put his hand on his heart and repeat his lies and he wouldn't," Mr Turnbull told reporters.
"He has been lying about Medicare and he's been caught out."
Mr Turnbull accused Labor and trade unions of calling older voters at night and "frightening them with lies".
"Now if somebody is running for prime minister and they're prepared to lie about something as important as that to vulnerable Australians, how can you trust anything else he says?"
Mr Shorten, for his part, accused the prime minister of having "his hand in the policy cookie jar".
"It is not what Malcolm Turnbull is saying now about a particular privatisation task force that's got me worried, what it is piece by piece, if given the chance, he will dismantle Medicare," he told reporters in Darwin.
Labor campaign spokeswoman Katy Gallagher denied Mr Shorten was softening Labor's line of attack.
"There hasn't been any change to Labor's position at all," she told reporters in Canberra.
"We are continuing to talk about our concerns about Medicare and potential privatisation."
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