Australia is being urged to "seize this moment" in the republic debate after almost all state and territory leaders signed a declaration calling for an Australian head of state.

Australian Republican Movement chair Peter FitzSimons says it's a "no-brainer" that Australia will become a republic, insisting support for the push is phenomenal.

He says the support from political leaders, including Prime Minister Malcolm Turnbull and Opposition Leader Bill Shorten, was no less than a "declaration of desired independence".

The only state leader who declined to sign was West Australian Premier Colin Barnett.


Mr FitzSimons said he was "bemused" by Mr Barnett's refusal to sign, saying the premier sent him a note insisting he was committed to the republican movement but wasn't keen to sign yet.

He believes Mr Barnett is worried about losing votes in the upcoming state election.

He's also suggested Mr Barnett's hesitation has to do with the premier's opening of Elizabeth Quay on the Swan River this week.

"He thinks he is going to lose votes. He won't lose votes on this," Mr FitzSimons told the Nine Network on Monday.

Mr FitzSimons also rejected suggestions the movement should wait until Queen Elizabeth II dies.

"Australia can do better than to find our heads of state from one family of unelected English people living in a palace in England.

"Have the Queen come when she is young enough and instead of bowing and curtseying, the nation rises as one in a standing ovation and says thank you your majesty, we will take it from here."

ACT Chief Minister Andrew Barr believes Australia's ties to the monarchy reflect a nation of the past.

"It's time for us to grow up and stand on our own two feet," he said.

Queensland Premier Annastacia Palaszczuk believes it's time for Australia to be led by one of its own while her South Australian counterpart Jay Weatherill thinks becoming a sovereign nation would profoundly change Australian mindsets.

The Australian Republican Movement wants a plebiscite on the republic by 2020, to be followed by a referendum if the initial vote is successful.

Mr FitzSimons says Australia would now go into a vote with united political leadership at the federal and state level, insisting the "euphoria" was building.

On Monday morning, a petition by Mr FitzSimons calling for a republic had only garnered 4200 signatures since Friday.