The turnout in Australia's same-sex marriage survey has passed that of the 2015 Irish referendum, with a month yet to run in the postal ballot.
In the second of a series of participation estimates, the Australian Bureau of Statistics (ABS) said on Tuesday that 62.5% of Australians had returned their survey forms by Friday October 6.
The percentage represents about 10 million eligible voters.
Forms must be returned to the ABS by November 7, with people encouraged to post them by the end of October. If survey forms have been lost or damaged, a new one can be requested by October 20.
Ireland's referendum on marriage in 2015, which passed with 62% of the vote, garnered a 60.5% turnout.
However, there are substantive differences between the two votes — Ireland had to have a referendum in order to amend its constitution to allow same-sex marriage, while Australia's non-binding survey was borne from tensions within the parliament and, specifically, the Coalition government.
Ireland also does not usually have compulsory voting, while Australians face a fine if they do not vote in regular elections and referendums.
Last Tuesday, the ABS said around 9.2 million people had returned their surveys by Friday September 29, in the first two-and-a-half weeks of the survey.
The rate of return has significantly slowed in the past week, with around 800,000 letters, or 5% of forms, sent back to the ABS in the past week.
Last month, current and former union officials with extensive experience in trade union postal ballots told BuzzFeed News that the window for a "get out the vote" campaign is very narrow.
"The experience of past postal votes is that anybody who doesn't vote within the first few days of receiving the paper, usually doesn’t," said former assistant secretary of the ACTU, Tim Lyons.
Roughly six million Australians are yet to cast their vote in the survey, which has been marred by complaints of stolen, lost, or misdirected ballots.
An Australian reporter living in New York wrote in Mother Jones on Tuesday that he had cast two votes with two separate online access codes — one gained via a request on the ABS website, and one mailed to him overseas.
A spokesperson for the ABS told BuzzFeed News it had measures in place to detect and prevent any attempts to vote multiple times, and that the "final processing" of valid and invalid forms would take place after November 7.
The ABS did not directly respond to a question on whether the observers selected by parliamentary committees for each side would be privy to the process under which any multiple votes are weeded out.
It has engaged consulting firm Protivi to provide "external assurance" for the survey.
"Protiviti will monitor a number of processes such as the survey preparation, dispatch of survey forms, survey receipt and counting, and destruction of forms," the spokesperson said.
Chair of the Senate inquiry into the postal survey, Jenny McAllister, told BuzzFeed News that acting special minister of state Mathias Cormann should reassure the public that the process is robust.
"Minister Cormann ought to explain how such a situation can come about, and whether the ABS is confident they can detect multiple voting by overseas voters," she said.
"He should also state transparently how many similar instances have been detected and how they've been remedied."
McAllister said she would bring the "troubling" report up in the next committee hearing.
Lane Sainty is a reporter for BuzzFeed News and is based in Sydney, Australia.
Contact Lane Sainty at firstname.lastname@example.org.
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