Labor Leader Bill Shorten insists when the referendum for constitution recognition of Australia's indigenous peoples is held, it will be a "fully formed proposition".

He has vowed to hold a referendum in the first term of his prime ministership should he win the May 18 election.

"I think it is long overdue for our First Australians to be in the nation's birth certificate, the constitution," Mr Shorten told reporters on the election campaign in Tasmania.

"It will be a fully formed proposition."

Read more Liberal and Labor MPs revive hopes for Indigenous Voice to Parliament

His comments came after Labor senator Pat Dodson, who would be the indigenous affairs minister in a Labor government, said voters would be given a guide on how a so-called "voice to parliament" may work.

But its final form would be decided by parliament if a referendum was successful.

Senator Dodson also wants "regional assemblies" if Labor wins power, giving indigenous communities across Australia an input into the body that would advise parliament on indigenous issues, The Australian newspaper reported on Saturday.

"Any model you come up with is always going to be subject to the parliament for modification," Senator Dodson says.

"So the model is simply 'This is how it may work'. The fully legislated entity that sets the model into place is a matter for the parliament to determine. That will always be the case."

But outgoing Indigenous Affairs Minister Nigel Scullion hit out at Senator Dodson's proposal.

"To take a referendum to the Australian people without a clear model of what the referendum will establish is the height of stupidity," he told AAP.

"Nonetheless, the Morrison Government remains steadfast in our commitment to recognising Aboriginal and Torres Strait Islander Australians in the Constitution."

AAP

He said the Morrison Government accepted the bi-partisan recommendations of the Joint Select Committee and is now working to implement them to deliver a pathway to a successful referendum.

"What Senator Dodson is suggesting Labor will do if elected will set back the cause of reconciliation," he said.

Liberal MP Julian Leeser, who helped write "a road map" for an indigenous voice, said this month Labor risked a Brexit-like failure if it rushed to a referendum.

Mr Shorten also supports a referendum for an Australian head of state, but says a vote to include First Australians in the constitution must come first.