Tony Abbott is urging the campaign against an Indigenous voice not to become complacent, warning the 'yes' side will try to "buy" a successful referendum.
The former prime minister has been a staunch critic of the Indigenous voice.
"I'm all in favour of proper respect and honour for the first Australians but I don't think anyone, however much we might admire them and appreciate them, should be given a special say," he told 2GB on Monday.
"I don't want to see our country divided by ancestry or by race and I don't want to see the business of government gummed up even further."
Voters will go to the polls later this year to determine whether the voice should be enshrined in the constitution.
Should it be successful, the voice would be able to make representations to parliament and the government on issues affecting Indigenous people.
While some polls have put support for the voice among young people almost as high as 75 per cent, others have shown overall support waning.
A Sydney Morning Herald survey showed NSW, Queensland, South Australia and Western Australia voting 'no' at the referendum, with support in Victoria and Tasmania only slightly above 50 per cent.
Four of the six states and more than 50 per cent of all Australians need to vote in favour of the voice for it to succeed.
Mr Abbott said the reduced support was "encouraging" but the 'no' side could not afford to be complacent.
"There is still an avalanche of money being provided by woke public companies, woke foundations and billionaires," he said.
"If it is possible to buy a referendum outcome, I think that the 'yes' campaign will do their best to buy it."
Nationals leader David Littleproud said his party would be willing to renegotiate with the government on the constitutional change, should a decision be made to delay the referendum.
"It depends on what the proposal is," he told Sky News.
"Constitutional recognition is something we're prepared to explore."
First Nations leaders gathered for the the Uluru Youth Dialogue ambassador program at the weekend, with co-chair Bridget Cama saying young people would play an important part in the referendum.
“Our young people are committed to this pragmatic reform that will achieve a better future for First Peoples and for this country,” said Ms Cama.
Renowned Indigenous activist Noel Pearson also issued a call to arms for the 'yes' campaign.
"We need to be at the railway stations, we need to be at the town halls, we need to be meeting people in the malls and we need to be appealing to the better angels of the Australian nature," he said.
Mr Pearson said a 'no' vote would leave Australia "in the darkness".
