Roundup: All but one Aust'n electorate support same-sex marriage: study

Just one of Australia's 150 electorates has a majority of voters against legalizing same-sex marriage, a new study has found.

The government, however, has warned the opposition not to block the public vote legislation as it would push back the landmark cause until at least 2020.

The Labor opposition has said it would block legislation for a public vote, or plebiscite, as it could affect the mental health of LGBTI Australians, but despite the uncertainty surrounding the future of the legislation, the University of Melbourne has found it would pass easily if it goes ahead.

The study found opposition to changing the Marriage Act ranges from just over 50 percent in rural Queensland and New South Wales-based electorates, to less than 10 percent in more progressive, inner-city electorates in major cities Melbourne and Sydney.

Researchers used modeling from the Australian Broadcasting Corporation's (ABC) Vote Compass survey from 2013 and found just a third of voters were opposed to same-sex marriage.

Political scientist Shaun Ratcliff from Monash University told Fairfax Media that while the study used three-year-old data and was not a direct survey of voting Australians, it comfortably showed that Australians were in favor of change.

"Based on our data and other polling, it appears a plebiscite would pass easily," he said.

"But at the same time there has been a majority in favor of same-sex marriage for quite a long time now. I don't think anything's inevitable but suspect on this particular issue we're going to see same-sex marriage legalized. It's just a matter of when."

Also on Monday, the government has yet again warned the Labor opposition against voting down the plebiscite legislation when it is introduced by the government, Attorney-General George Brandis told Fairfax Media that should the legislation get voted down, same-sex marriage would be placed on backburners until at least 2020.

"The government is prepared to negotiate with the Labor Party in good faith because we are committed to resolving this matter by a plebiscite. That was endorsed by the Australian people at the last election," Brandis said.

"And if (they) favor reform to the Marriage Act to allow same-sex couples to marry then this is now the only feasible path to that outcome for many years to come."

Brandis said the government was in favor of giving Australians the right to vote on the legislation, and said it would be a shame if Labor robbed Australians of that right.

"It would be a real tragedy to have three marriage equality bills and no legalization of marriage equality," he said.

"We want this to be cross party and it needs to pass by whatever pathway."

Labor has consistently opposed the plebiscite, which would cost up to 100 million U.S. dollars, as they fear the vicious "no" campaign would have a negative psychological effect on the mental health of young LGBTI members of the community.

The party has suggested a conscience vote at the parliament, while same-sex marriage advocates have supported Labor's position, calling for MPs to make decisions and do what they were voted into parliament to do. Endit