Australians have had their say in the same-sex marriage debate, with more than 12.6 million ballots received before the survey officially closed.
According to the latest estimate, 78.5 per cent of eligible voters had returned a ballot as of Friday.
Same-sex marriage advocates on Tuesday issued a public call for anyone who'd left it until the last minute to hand-deliver their vote by the 4.30pm cut-off.
"We are grateful for the amount of Australians who have participated in this process," equality campaign Alex Greenwich told reporters outside the Australian Bureau of Statistics office in Sydney.
"A strong majority of Australians support a fair go for all and want everybody to be able to marry the person that they love in the country that they love."
City of Sydney councillor Christine Foster, the sister of former prime minister and outspoken 'no' vote advocate Tony Abbott, said the signs were looking positive.
"All the signs are really positive; the high turnout, exit polling and that would really be a seminal national moment for Australia; it will be a unifying moment," she said.
Olympic swimming champion Ian Thorpe was reassured by the number of people who'd already returned their vote ahead of the deadline.
"Considering how many people in Australia have voted for this, it's quite reassuring because we know over recent decades how many people have supported marriage equality," he told AAP at the Melbourne Cup.
"We are hoping its an overwhelming positive 'yes' result and it leaves our politicians with no excuse but to get on with it."
The 'no' campaign said its team members were looking forward to some days off.
Spokesman Lyle Shelton said even if the 'yes' vote prevailed, the 'no' campaign would need to hold same-sex marriage supporters to their pledge about there being no negative consequences of reform.
"We promise our supporters that no matter the result, we will continue to work to defend Australian families," he said in a statement.
Mr Shelton said the 'yes' side had already said it would continue pushing for legal same-sex marriage even if the survey result was a 'no'.
"Even if we win, we will be need to continue to fight to defend marriage and to protect Australians from the consequences of its redefinition."
In a new Essential Poll of 1792 people, published in The Guardian on Tuesday, 64 per cent of respondents said they had ticked the 'yes' box.
Thirty-one per cent were 'no' voters and five per cent declined to answer.
The ABS will now devote its resources to counting the ballots before the result is announced and published on its website on November 15.
