The postal survey, which cost $122 AUSD million, asks voters to answer either ‘yes’ or ‘no’ the question ‘should the law be changed to allow same-sex couples to marry?’

Although the results of the survey are not legally binding, Prime Minister Malcolm Turnbull has stated that parliament will discuss amending the Marriage Act if the majority of those surveyed say they support same-sex marriage.

So far 12.6 million (78.5%) of the 16 million eligible voters have returned their ballots. At the last survey, 64% reported having ticked ‘yes’ and 31% having ticked ‘no’.

However, political commentators have urged caution, given less-than-accurate poll predictions of recent times. Still, Yes campaigners remain hopeful.

“We are hoping its an overwhelming positive ‘yes’ result and it leaves our politicians with no excuse but to get on with it,” said marriage equality campaigner and Olympic swimming champion Ian Thorpe.

Voting now closed in Australia! Sending love to Oz campaigners for running an energetic, positive campaign. 12.6 million (78.5%) ‘voted’! pic.twitter.com/VqP0xDxSsJ

— Love Equality NI (@Love_EqualityNI) November 7, 2017

Marriage equality advocates had expressed dismay at the choice of a postal survey to gauge attitudes towards gay marriage, arguing that “the extra hurdles of updating enrolment and remembering to post a letter” would discourage participation from young Australians.

Several marriage equality advocacy groups, including Rainbow Families, Australian Marriage Equality, took challenges against the postal survey claiming that the Australian Bureau of Statistics was not legally capable of conducting such a survey. In September 2017, the High Court ruled against the plantiffs.

The campaigning around the survey became contentious when marriage equality opponents such as the Coalition for Marriage, released television ads warning parents against voting Yes. Yes campaigners responded with a video featuring celebrity doctor Kerryn Phelps.

“Sadly, some are trying to mislead us like this ad does, by saying there will be a negative impact, including on young people,” Dr Phelps says in the ad. “The only young people affected by marriage equality are young gay people who for the first time will have the same dignity as everyone else in our country and they deserve that.”

The results of the survey are expected to be announced on Novemeber 15.