Labor leader Bill Shorten has urged the Prime Minister to break the shackles of monarchists in his government and lead the push for Australia to become a republic.
The call comes after all the state and territory leaders expressed support for a republic amid a push for a plebiscite for an Australian head of state by 2020. 
Mr Shorten is expected to use his Australia Day address in Melbourne on Tuesday to call for Malcolm Turnbull to drop his insistence that constitutional change is only possible after the end of the Queen's reign.
Seven of the eight state and territory leaders have signed a declaration by the Australian Republic Movement calling for an Australian head of state. WA premier Colin Barnett did not sign the declaration but confirmed he supported a republic.
Mr Shorten noted that both he and Mr Turnbull, a former ARM chairman, supported a republic.
"For the first Australia Day in our history, the leaders of both major parties are avowed republicans," he said. "So today I say to the Prime Minister, let us work together to seize this moment, to lead the movement for change."
Beyond saying his passion for a republic remained "undiminished", Mr Turnbull has declined to react to ARM's "declaration of desired independence".
But cabinet minister Mitch Fifield, a republican, said the debate was not a priority for the government. "My view is that this proposition won't seriously be re-examined for so long as the Queen is on the throne."
Treasurer Scott Morrison said he favoured the current constitutional arrangements.
"The real thing we celebrate on Australia Day, I think, is our freedom as a people and the great opportunities we have and I would like to see Australians have more of them," Mr Morrison said.
ARM chairman Peter FitzSimons said he was bemused by Mr Barnett's refusal, saying the Premier sent him a note insisting he was committed to the republican movement but wasn't keen to sign yet.
Mr FitzSimons believes Mr Barnett's hesitation may have something to do with the Premier's opening of Elizabeth Quay on the Swan River this week.
However, a spokeswoman for Mr Barnett said there was no link.
South Australian Premier Jay Weatherill says it would be appropriate for the Queen to oversee the change.
"It would be the ultimate act of respect to Queen Elizabeth if she presided over the transfer of Australia from a monarchy to a republic," Mr Weatherill said. "What are we waiting for? Are we waiting for her to die? I would have thought that it's much more respectful to have her supervise this transition."
The ARM wants a plebiscite on the republic by 2020, to be followed by a referendum if the initial vote is successful.
Australian Monarchist League spokeswoman Gabrielle Hendry said the majority of Australians were opposed to becoming a republic.