Malcolm Turnbull is trying to recast the future of an embattled Labor senator as a test of Opposition Leader Bill Shorten's loyalty to the country he hopes to lead.
Mr Shorten has lost faith in Sam Dastyari and sacked him from two Senate leadership roles, but rejected calls to dump him from Labor over his involvement with a Chinese political donor.
But the prime minister says that's not good enough.
"It's time for Bill Shorten to show he's really on Australia's side and boot Dastyari out," he told Sky News on Sunday.
The Labor powerbroker is under fire after it was revealed he defied party policy when he defended China's stance on the South China Sea at a media conference attended by Communist Party-linked political donor Huang Xiangmo.
He also reportedly told Mr Huang they should leave their phones indoors and speak outside during a meeting at the businessman's home, with concerns the donor's mobile was being tapped.
Mr Turnbull said if Mr Shorten wanted to lead Australia, he must look out for for the country's interests.
"We know that (Senator Dastyari) has been taking money from and providing counter-surveillance advice to a foreign national with the closest links to a foreign government," the prime minister said.
"In those circumstances, Shorten should stand up for Australia. His failure to do so means that he puts his factional survival, which depends apparently on Senator Dastyari, ahead of the national security of the country he wants to lead."
Mr Shorten has said he's confident Senator Dastyari had not broken any law and was not a security risk.
But Mr Turnbull hinted on Sunday the senator may be under investigation, although he hasn't asked police or security agencies to look into it.
"This is a political matter and ... I don't give directions to our police or our security agencies on operational matters," he said.
"You shouldn't assume it's not being investigated."
Labor frontbencher Tim Hammond dismissed the prime minister's attack as the move of a desperate politician with "absolutely nothing else to go with in relation to any meaningful agenda of his own".
"We've been very transparent and Bill has been very clear and very firm in relation to his disappointment as to Senator Dastyari's remarks and conduct," he told Sky News.
