Getting indigenous recognition right is more important than holding the national vote on a symbolic day, Referendum Council co-chair Mark Leibler says.
A referendum to recognise indigenous Australians in the constitution won't be ready by the proposed date of May 2017, dashing hopes of a vote to coincide with the 50th anniversary of the 1967 referendum.
It would've been nice to have met the deadline but it's more important to get it right, Mr Leibler says.
The council has announced it will continue consultations into next year with a view to presenting a final report by mid-2017.
"This is the first time that our indigenous people ... have ever been invited to design their own consultations," he told ABC radio.
"They need to get it right, they're taking this very seriously."
Mr Leibler said talk of treaty "may well impact" on what emerges from the consultations, insisting the matter was "on the table".
"What we may well end up saying is 'here is a proposal for amending the constitution - but if you want to guarantee its success ... you need to understand there are other issues around and treaty may be one of them'."
Other issues that may have an impact are the timing of the same-sex marriage plebiscite and the royal commission into the Northern Territory juvenile justice system.
In 1967, more than 90 per cent of Australians voted for the inclusion of indigenous Australians in the national census and a new commonwealth responsibility for indigenous policy matters.
