Giving Australians a say on gay marriage could have mental health consequences, experts warn, amid calls for a postal plebiscite on the matter.
National Mental Health Commission chairman Allan Fels says there could be mental health impacts for both the gay community and opponents of gay marriage arising from a debate on same-sex marriage if a plebiscite goes ahead.
"People get very stressed about this topic and debates can get out of hand," Prof Fels told the National Press Club on Tuesday.
"The commission has often said that the mental health of the LGBTI community is not good.
"The numbers are really bad for the LGBTI community."
Cabinet minister Peter Dutton's idea of a postal plebiscite has been criticised inside the coalition, with Liberal senator Dean Smith labelling it "corrosive".
Senator Smith, who is drafting his own private member's bill for a conscience vote in parliament, acknowledges the latest idea demonstrates a willingness to deal with the issue, but he is wary of the cost and legal hurdles.
"We have had two binding plebiscites previously in 1916 (and) 1917. They were acrimonious and they divided communities," Senator Smith told ABC radio on Tuesday.
"Postal plebiscites, national plebiscites are corrosive to our representative parliamentary democracy."
Senator Smith says his bill for a free vote before year's end will be made public and is a sensible and constructive way forward.
A ReachTEL poll for activist group GetUp says 70 per cent of those surveyed in Mr Dutton's own electorate want a free vote in parliament.
Just 24 per cent of the 708 Dickson residents disagreed that the government should allow a free vote.
Prime Minister Malcolm Turnbull insists his party took a plebiscite policy to the election and to change it would be breaking a promise.
Former prime minister Tony Abbott concedes a vote via the post would be better than parliament.
But he too questions how much real authority a postal plebiscite would have.
Deputy Prime Minister Barnaby Joyce is happy to have a discussion about holding one.