Now happily married with two children after travelling to New Zealand to wed again, Sam could not bear the devastation of a vote against same sex-marriage by the public or by Parliament.

"Even though it is just an opinion poll, if people voted against our family in a plebiscite, or if the legislation then didn't get through Parliament, it would feel like sitting there having my marriage taken away all over again," she said.

"I don't want my son watching TV ads telling him his family is not OK or have to answer questions at school."

As same-sex marriage was thrust back into the spotlight in the final days of the 2016 federal election, the Wilsons are one of many gay couples to share their views on the issue.

While against a same-sex marriage plebiscite, which Prime Minister Malcolm Turnbull said could be held by the end of the year if the Coalition is re-elected, she does not trust Opposition Leader Bill Shorten's claim that he would make same-sex marriage his first legislative act if Labor wins the election, suspecting it's an empty promise made to gain voters.

A 2015 study by Roy Morgan research found one-third of Coalition voters, 15 per cent of ALP voters and 4 per cent of Greens voters believed homosexuality was immoral.

Canberra was the eighth electorate in Australia to most strongly disagree with the statement, following seven electorates in Victoria or NSW.

Canberran Patrick O'Brien hopes the nation will soon move beyond polls and surveys and have "given equal human rights" to him and his fiance Troy, who plan to someday marry on the rooftop of their favourite hotel, overlooking the beaches of Byron Bay.

He is concerned about the large cost of a plebiscite, though a disputed figure, and that it would only be voluntary.

However, earlier this week Mr Turnbull said for the first time that he expects the vote to be compulsory, similar to a referendum. But he said that none of his MPs – including cabinet ministers – will be bound to support the public's verdict.

For Holly Hafner and her girlfriend Sal, the biggest worry is that a plebiscite would intensify homophobia.

"We should not allow the population to voice their opinion on the value of the love shared between two people," Ms Hafner said.

"So why execute prejudice based on the fickle definition and outdated norms?"

A few days earlier, Mr Shorten promised legalising same-sex marriage would be his government's first priority in Parliament.

The Greens have also expressed strong support for marriage equality.