Australians have one last chance to mail their marriage equality form before the postal survey closes on Tuesday.
The marathon campaign is almost at an end, and any forms received after 6pm on Tuesday will not be counted by the Australian Bureau of Statistics (ABS).
The results will be announced on Wednesday, November 15 around 10am (AEDT).
Most opinion polls show the 'yes' vote winning with around 60 per cent, but an academic study of Twitter opinions refutes that.
Griffith University professors David Tuffley and Bela Stantic used advanced data analytics which they say have proven accurate at predicting the outcomes of hard-to-call polls, including the 2016 US presidential election.
After running their algorithms, support for 'yes' came in at 49 per cent.
The 'yes' campaign has been well supported by a number of high-profile Australians with Julie Bishop revealing that she had voted 'yes'.
The Liberal Party's deputy leader joins Prime Minister Malcolm Turnbull and Opposition Leader Bill Shorten in the 'yes' camp.
Even if the 'yes' vote does win, there is no guarantee marriage equality will pass the House of Representatives.
