The prime minister says Australia will stay the course and head to the polls as scheduled, despite a last-ditch appeal from the opposition to scrap the Indigenous voice referendum.
Anthony Albanese returned from a series of overseas summits on Monday and told parliament the referendum would go ahead on October 14.
Opposition Leader Peter Dutton urged the prime minister to scrap the vote to avoid dividing the nation.
"Australians will get to determine their view on that date," Mr Albanese told parliament.
Governor-General David Hurley issued the referendum writ on Monday after a meeting of the executive council in Canberra.
Overall support has slid to new lows with every state except Tasmania set to vote 'no' to a constitutionally-enshrined consultative body for Aboriginal and Torres Strait Islander people.
A Resolve Political Monitor survey, published in Nine newspapers on Monday, showed 43 per cent of voters supported a plan to enshrine an Indigenous voice in the constitution, down 20 percentage points from a year ago.
The percentage of Australians in favour of the plan has dropped for the fifth month in a row and Victoria has flipped to a majority 'no' state since the previous survey.
A successful referendum will require a 'yes' vote from more than 50 per cent of voters in four of the six states.
Environment Minister Tanya Plibersek said there were still many undecided voters who could be convinced to vote 'yes', adding the purely consultative body with no veto power was "a lot less scary than some of the 'no' campaign are making it out to be".
Yes23 spokesman Dean Parkin said the majority of campaigners and volunteers he saw out doorknocking around the national were in the 'yes' camp.
"We knew that we would be in this position in the lead-up to the final vote," he said.
"But it's very clear about what we need to do, we need to get out there and have as many conversations as we possibly can between now and the referendum."
Independent senator Jacqui Lambie said the government had "failed miserably" in its bid to sell the positives of the voice and provide detail.
But she also rejected the opposition's pledge to hold a second referendum on constitutional recognition as a "brain fart".
Nationals leader David Littleproud said the prime minister needed to split the question to avoid dividing the nation, with most people supporting constitutional recognition of Aboriginal and Torres Strait Islander people.
He denied a failed referendum would send a negative message to Indigenous Australians, saying it would be viewed as a rejection of the prime minister's model.
"Many Indigenous Australians feel that view now and that's why I think it's wrong for Indigenous leaders who support 'yes' to ... make generalised statements about how Indigenous Australians will feel," Mr Littleproud told reporters in Canberra.
Postal vote applications close on October 11.
The electoral roll closes seven days after writs are issued, meaning people have a week to ensure they're enrolled.
Hundreds of early voting centres will be available from October 2, with centres to open in the ACT, NSW, Queensland and South Australia a day later due to a public holiday.