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Australia looks set to have same-sex marriage by the end of the year, with more than 60% of the population voting ‘yes’ in the federal government’s postal survey according to new research from Roy Morgan.

The ‘yes’ vote is out-polling the ‘no’ side by a ratio of 3-to-1, but around a fifth of the country didn’t respond or said they didn’t intend to vote when asked in a Roy Morgan Snap SMS Survey on the October 6-8 weekend.

The poll of 1,554 Australians aged over 18 found 61.5% were voting ‘Yes’, and 17.5% ‘No’ while 21% didn’t answer or have no intention of voting. Each state had a majority in favour of same-sex marriage (SSM).

Voting intentions on same-sex marriage. Source: Roy Morgan Research

Roy Morgan Research CEO Michele Levine, Chief Executive Officer said her company’s survey confirmed the view that the issue divided people along the lines of age and which political party someone supported

“Significantly there is little variance between different States with majorities in each State voting in favour of the change. This is important as several Liberal and National senators and MPs have pledged to follow either the overall national vote, the vote in their State, or the vote of their own electorate in deciding whether to vote in favour of same sex marriage legislation,” she said.

“The takeaway from this special Roy Morgan Snap SMS Survey is that once results are officially announced on November 15 in a month’s time the Parliament, which is sitting in the last week of November, will likely pass a bill legalising same sex marriage before the end of the year.”

Levine says the likely outcome also offers Prime Minister Malcolm Turnbull a personal “victory” over the Liberal party’s more conservative forces.

“The added benefit for PM Turnbull is that with the issue resolved it can’t be used against the Government by the Opposition in the lead-up to the next federal election,” she said.

In a breakdown of political allegiances, support for SSM was highest amongst Greens voters at 92%, following by the ALP at 77% of ALP supporters. Liberal and National supporters where either indifferent or apathetic, with less than half having so far voted, or intending to vote “Yes”.

A clear majority of women (66.5%) are in favour of the reform, well ahead of men (56%), with nearly twice as many men (23%) saying they’ll vote no compared to 12.5% of women.

Age plays a huge part in support for yes, with 81% of 18-24-year-olds in favour before support slides as people age, although the majority remain on the yes side up until age 65. That large majority continues up until 50, with 70% of those aged 25-34 in favour of SSM and 69.5% of those aged 35-49 also supportive. But the “yes” figure drops dramatically to 52% in the 50-64 age bracket before falling to 48.5% in the over 65s.

Voting intentions on same-sex marriage by age. Source: Roy Morgan Research

Australia’s ageing population plays a key role in the lower overall national figure, but also shows that one of the key arguments of the “no” campaign, that marriage is for children, holds little sway among the age demographics who can actually have children.

Victoria tops the states in favour at 69.5%, which Levine says in now surprising when it’s the only place with a Greens MP in the lower house – Melbourne’s Adam Bandt, while South Australia, home to outspoken no campaigner and Coalition defector senator Cory Bernardi, is at the bottom of the support table at 55.5%, just below Queensland on 57%.

Voting intentions on same-sex marriage by state. Source: Roy Morgan Research

Roy Morgan also asked people about why they made their decision and the answers show that the arguments put by both sides of the debate are at the forefront of voter rationale.

‘Yes’ voters most frequently cited equal rights for everybody, equality before the law, social justice, that everyone should have the right to marry, that it is discriminatory to think otherwise, because love is love, and human rights.

Roy Morgan says very few respondents said they were just “over” the issue in general, and were voting yes to settle the issue once and for all.

Among ‘No’ voters, the “thin edge of the wedge” was the most commonly held argument, alongside worries about how this may impact other religious and relationship beliefs down the track.

The “slippery slope” also featured.

“I would like to avoid the slippery slope, the indoctrination of children in schools, and the celebration of homosexuality as normal. It’s an aberration, and mustn’t be called marriage,” one respondent said.

Others mentioned it was a personal belief, “if it ain’t broke, don’t fix it”, and many expressed simply that they understood marriage to be between a man and a woman, Roy Morgan found.

“Personally I have no problems with same sex couples and have friends that are in same sex relationships but there’s more at stake than that. I don’t trust where this leads us with bigger agendas and politicians so in that light I voted the way I did,” one respondent said.

While religious beliefs were mentioned as a reason, along with free speech concerns, others said the way the ‘Yes’ advocates campaigned had turned them into ‘No’ voters and felt bullied.

“I don’t like being bullied into a yes vote by the media or the vote yes text. And while I’m not religious I am concerned about the impact on religious freedom,” one person said.

Others told the researchers their reasons were “None of your business”.

Voting in the same-sex marriage postal survey closes on Melbourne Cup Day, November 7. The results will be announced on November 15.

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