The failure of the 1999 referendum was blamed in part on this model, derided as the "politicians' republic" by both republicans favouring direct election and monarchists.

Mr Turnbull, who headed the Australian Republic Movement as a private citizen for the referendum, said he did not expect republicanism to become a frontline issue until the end of the Queen's reign.

He would not be drawn on whether he would put a referendum to the people if the Queen died while he was in office but if it eventuated, the first priority was settling on the model for selecting a president by either bipartisan parliamentary appointment or direct election.

He suggested this could be done with a postal survey, alluding to the success of last year's public vote to legalise gay marriage in which almost 80 per cent of Australians participated at a cost of less than $100 million.

Malcolm Turnbull at North Bondi Surf Life Saving Club in Sydney on Monday. Mick Tsikas

"We all say 'long live the Queen' and we say that with great sincerity and love," Mr Turnbull said.

"If you are asking me how you would go about it in the event of the issue becoming live again I think the first thing that you would need to do is to have an honest, open discussion about how a president would be elected. That was the rock on which the referendum foundered in 1999.

"You've got to have that discussion and it may be that a plebiscite or it may even be a postal survey given the success of the marriage postal survey. That issue needs to be debated and resolved and then of course the fundamental question you've got to put up an amendment to the Constitution which proposes a president to replace the Queen as head of state."


Labor's position is if it wins the next election it will ask voters whether Australia should become a republic, and use its second term to determine the model.

"If Turnbull is committed to an Australian republic he should outline a plan, not come up with random thought bubbles," opposition republic spokesman Matt Thistlethwaite said.

The Australian Republican Movement's head, ex-Wallaby and journalist, Peter Fitzsimons, said on Twitter "we welcome the return of the PM - long the most passionate republican in the country - to moving forward the process of becoming a republic".

But Australians for a Constitutional Monarchy national convener David Flint said it was "ridiculous" for the PM to weigh into the republic debate at a time when pressing action was required on energy prices, terrorism and ethnic gang crime, adding support for a republic had dwindled since 1999.

"The chances of him being prime minister at the end of the Queen's reign are pretty minimal," Professor Flint said.

"I don't think he has any sense of priority."

In an interview with News Corp to mark the release of the cabinet papers, Mr Keating claimed his followers in the top job - Liberals John Howard, Tony Abbott and Mr Turnbull, and Labor's Kevin Rudd and Julia Gillard - had broken the nation's heart by failing to progress the matter.

Mr Keating labelled Mr Turnbull, who he appointed to head the Republic Advisory Committee, a "chameleon" on the republic.


Mr Turnbull said Mr Keating's criticism was "barely coherent".

"He seems to be critical of every prime minister and former prime minister apart from himself. It must be good for Paul to feel he is without fault or blemish," Mr Turnbull said.

Mr Abbott, who was a prominent campaigner against the republic in 1999 and remains a staunch monarchist, shot back at Mr Keating on social media.

"We don't need to dump the Queen to be a great country. Republicans will never win by running Australia down," he said on Twitter.