Albanese will unveil the date at an event in Elizabeth on Wednesday, with October 14 widely tipped, setting the scene for a six week national campaign.

The Prime Minister will be joined by Minister for Indigenous Australians Linda Burney and other members of his cabinet, along with Premier Peter Malinauskas.

South Australia and Tasmania are widely viewed as critical swing states as supporters start to fire up their ground campaign.

While previous polls had put the ‘no’ vote ahead in South Australia, a new survey of 605 people indicates 43 per cent of South Australians now back an Indigenous voice to parliament, while 39 per cent are opposed.

The undecided 18 per cent were evenly split in their leaning, putting the ‘yes’ vote ahead at 52-48.

The Australia Institute poll held in early August also found that 56 per cent of South Australian women are inclined to vote yes, while 52 per cent of men are inclined to vote no.

The poll found that 81 per cent of South Australians aged 18 to 29 are inclined to vote yes, along with 63 per cent of those aged 30 to 39.

Those aged between 40 and 59 were more evenly split between a yes and no vote, while 66 per cent of those aged 60 and over are inclined to vote no.

The poll also found that 65 per cent of South Australian Labor votes were inclined to vote yes, while 68 per cent of Coalition supporters backed a no vote. Amongst Greens voters, 72 per cent were inclined to vote yes, while 83 per cent of One Nation voters said they would vote no.

“Our research shows that, with a majority of South Australians currently inclined to supporting the Voice at the upcoming referendum, it is young women who are leading the way and are most likely to be intending to vote Yes,” said Australia Institute SA director Noah Schultz-Byard.

“If young South Australians want the referendum to succeed, it’s clear that they need to talk to their parents and grandparents about why they so strongly support the Yes vote.”

Other polls have the ‘yes’ vote lagging across the nation and on a downward trend, but campaigners say the mood on the ground is more hopeful.

Speaking in Adelaide on Tuesday, Indigenous activist Noel Pearson said the state would be critical in the referendum.

“It’s really a linchpin, it’s been between those eastern states that are very firmly ‘yes’ and those that are still pondering what they will do at this referendum,” he said.

Albanese has previously ruled out multiple weekends for the referendum including footy grand finals, parliament sitting weeks and the wet season in the Northern Territory, essentially putting it in mid-October.

‘Yes’ supporters will kick off campaigns across the country, including door knocks and street walks.

To succeed, a majority of states need to vote ‘yes’ as well as the majority of Australians.

Supporters of the voice face an uphill battle with the vast majority of Australian referendums failing and the federal opposition campaigning heavily against the constitutional change.

The ‘no’ campaign has positioned the voice to be legally risky and divisive along racial lines.

Former prime minister John Howard warned a successful voice referendum would lead to calls for treaty.

“We don’t have treaties with bits of ourselves and it only has to be stated to be realised as a complete absurdity,” he said.

“Treaties are made between sovereign nations, we have treaties with other countries.”

-with AAP