The two authors of the Indigenous Voice co-design report say the argument that it lacks detail is disappointing, saying they personally went through the report and findings with multiple parliamentarians.
Professors Tom Calma and Marcia Langton produced the Indigenous Voice Co-design report over two years and thousands of consultations, presenting the report to the then-Morrison government last year.
The pair said it was concerning the Nationals have used the "no detail" argument to justify standing against the Voice.
"We cruised the corridors of Parliament House over and over again and tried to speak to as many people as possible — and we did speak to Nationals and to Liberal Party members," Professor Langton said.
"I'm really quite disappointed that people don't believe that we haven't spoken to them when we in fact did and that they believe that there's no detail when we've personally handed the report to them and discussed it with them.
"It's unfortunate that the Nationals have injected misinformation and vitriol into the debate so early on."
Professor Langton said it was especially disappointing that Northern Territory senator Jacinta Nampinjinpa Price has been the driving force behind the Nationals' position.
"I'm terribly disappointed that a Warlpiri person or a Celtic-Warlpiri person has kicked this off," she said.
"It would be terribly unfortunate for all Australians, if the debate sinks into a nasty eugenicist, 19th-century style of debate about the superior race versus the inferior race.
"We have to take these matters seriously, this is too important to play nasty electoral politics about."
Professor Calma said the Coalition has had the detail on the Voice proposal for a long time.
"It's worth saying that the final report also went to cabinet and had been discussed for almost six months amongst the Coalition members before it was finally released again unchanged and released to the public in December last year," he said.
More detail on the Voice in the new year
Both Professor Langton and Professor Calma are now part of the referendum working group, one of two groups tasked with providing independent advice to the government on the referendum on a Voice to Parliament.
It's understood the group is currently looking at the wording of the question to be put to public and the timing of a referendum.
Professor Calma said there should be more detail coming from the group early next year.
"We're still just consolidating our position at the referendum working group level, and once that's done, we'll come out and that'll be in the new year, with a bit more detail," he said.
"We're taking our time because we know the referendum won't happen until the end of next year at the very earliest, or early in 2024."
The government is yet to put forward the exact model it intends to pursue if the referendum is successful, but Professor Langton said she believes it would be similar to the co-design report.
"I'm very confident that the Voice will look much like our proposal, our detailed proposal in our final report," she said.
"I can't imagine that there is a better model out there, I can foresee some tweaks, but we put in over two years of work, we consulted thousands of people."
Speaking with ABC's Insiders, Indigenous Australians Minister Linda Burney said she wouldn't undercut the work the referendum working group and engagement groups were doing by making an early announcement.
"The Voice is being informed by two very important First Nations groups," Ms Burney said.
"We're not going to get ahead of the working group. I have been involved in Aboriginal affairs for over 40 years, and I know the importance of consultation.
"We are being very deliberate and being very careful and listening to all the voices. The report, the Calma-Langton report is absolutely fundamental, obviously, to what will be the final design of the Voice. It's not the only report, but this is not something that has come out of nowhere."
