The defence minister is being urged to haul backbencher Ed Husic into line after the Labor MP broke ranks to call for a rethink of the AUKUS nuclear submarine deal.
Mr Husic went public with his reservations about the pact following revelations Australia will only get second-hand submarines from the United States.
His comments follow Midnight Oil frontman and former Labor minister Peter Garrett announcing plans for an independent "people's inquiry" into the national security implications of AUKUS.
Mr Husic, who also questioned the deal during a private caucus meeting on Tuesday, said Australia needed to reconsider its commitment to the deal with the US and the UK because America was becoming an increasingly unreliable ally.
"You do wonder whether or not we will get the deal, even the reconfigured one that we have got," the western Sydney MP told reporters at Parliament House.
Australia was set to get a mix of new and used Virginia-Class vessels before eventually building its own in Adelaide, but now the defence force will only get used submarines.
Defence Minister Richard Marles defended the move, saying it would make AUKUS simpler and cheaper to deliver, but Mr Husic appeared skeptical.
"In the circumstances he's been placed, he would have to say that," Mr Husic said.
The Labor MP, who was science and industry minister before being ousted from cabinet in 2025 in a factional power play, said Australia needed to be open about the workforce shortages, supply chain challenges and quality issues confronting the AUKUS pact.
Mr Husic has previously broken with his colleagues on the recognition of a Palestinian state, the war in Gaza and taxation of gas.
Opposition defence spokesman James Paterson said the defence minister needed to pull Mr Husic into line and suggested the comments could undermine Australia's relationship with the US and UK.
"It's absolutely legitimate to ask questions about how this government is going about delivering AUKUS ... the answer to those concerns is to double down," he told reporters in Canberra.
"The answer is not to scrap it altogether as Ed Husic is proposing."
Mr Garrett on Tuesday announced plans to lead a community-based inquiry into AUKUS, investigating the implications of the pact for the nation's security.
The crowdfunded probe, run separately from the government, would look into whether the vessels would make Australia more secure, the storage of nuclear waste and potential long-term strategic consequences, the former environment minister said.
"This is not a royal commission, this is a people's inquiry," Mr Garrett said in Canberra.
Mr Garrett said he hoped the government would be among those presenting to the inquiry and welcomed submissions from people with a range of political views.
"The AUKUS decision is the most momentous and expensive decision ever made by any Australian government in the modern era," he said.
The rock star turned politician has named retired admiral Chris Barrie, former Western Australia premier Carmen Lawrence, Yankunytjatjara woman Karina Lester and Australia Institute co-chief executive Leanne Minshull as "commissioners'' for the probe.
Mr Barrie, who was chief of the defence force between 1998 and 2002, said it was important to have a thorough look at Australia's defence commitments and its alliance with the US and UK.
"My fear ... is that the kinds of expenditures, and the kinds of workforce, and the way in which we would go about supporting something like AUKUS, might drain other parts of our defence force," he said.
Asked about Mr Husic's contribution during Labor's caucus meeting, Treasurer Jim Chalmers would not be drawn.
"We support the AUKUS arrangements and I don't get into the details of discussions in the parliamentary party," he said.
WA Labor MP Josh Wilson has also previously raised questions about the nuclear submarine deal.
