CANDIDATES for Flynn have declared their stance on legalising same-sex marriage, as a new website has put pressure on candidates to come out and declare their support.

Incumbent LNP member Ken O'Dowd has said "95% of the electorate" was against legalising same-sex marriage - while Labor candidate Chris Trevor insists that "the majority of Australians" support it.

Mr Trevor and independent Craig Tomsett have backed gay marriage, while Mr O'Dowd and Richard Love said the Marriage Act should be "left as it is".

The Palmer United Party backs a conscience vote, and candidate Steve Ensby said he would stand with whatever outcome the vote delivered.

Marriage equality came third in an Australia Institute survey of more than 800 people aged 17-25, who were asked the top five issues likely to sway their vote.

Australian Marriage Equality deputy chief Ivan Hinton said voters were being encouraged to go to the Vote4Love website to see which candidates support marriage equality.

"We're getting a lot of positive feedback from new Liberal candidates that they are willing to support it... I think they understand that marriage equality is something any new candidate needs to be behind," he said.

But Mr O'Dowd, LNP candidate for Flynn, said he was convinced to leave the Marriage Act as it was, after last year's 98 to 44 parliamentary vote - although the Coalition had to toe the party line.

"At the moment my electorate is telling me to leave it as it is," he said.

"Until I get signals from my electorate to say anything different, I'll stay with that."

Richard Love agreed, saying the "institution of marriage should be left the way it is".

But Chris Trevor, whose party allows a conscience vote, said he'd back gay marriage if Labor introduced legislation within the first 100 days of parliament.

He said he came to the decision as a father, who would want to support his children if they were gay.

"Yes I will vote for gay marriage, out of personal belief, and yes the majority of Australians overwhelmingly support this proposal," he said.