About 9.2 million Australians – 57.5% of the 16 million eligible voters – had returned completed forms by last week, the Australian Bureau of Statistics (ABS) estimated on Tuesday, reports BBC.

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.

Both sides have welcomed the earlier postal returns as a promising result with Yes campaigners citing similar high voter turn-out in favour of same-sex marriage during Ireland’s 2015 referendum.

“Feedback from our volunteers making phone calls suggest Australia is saying Yes to love, Yes to fairness and Yes to equality,” said Sally Rugg, director of GetUp Marriage Equality.

“We were initially concerned about the vote being held via the post because the extra hurdles of updating enrolment and remembering to post a letter, so it’s heartening and exciting to see such huge participation in the survey,” Rugg told News.com.Au.

Spokesman for Coalition for Marriage, who oppose same-sex marriage, Lyle Shelton, said that the conversation is “still wide open”.

“The statistics released today tell us that one in two Australians are yet to participate in this survey, and we want to make sure everyone has their say. Half of the country is yet to make up its mind; this conversation is still wide open.

“Our campaign will continue tirelessly until the final person casts their vote and the ballot closes.”

The ABS released the estimate in the hope of encouraging an even greater number of responses. “We hope that this update will serve as a reminder to those who have not submitted their form to do so promptly if they wish to have their say,” said ABS Deputy Statistician Jonathan Palmer.

Respondents have until November 7 to return their postal ballots.