Josh Frydenberg won't join a same -sex marriage campaign but will urge his electorate to vote yes.
Senior Liberal Josh Frydenberg won't be drawn on how many same-sex marriage postal votes need to be returned to make it legitimate.
The cabinet minister supports same-sex marriage and will be encouraging as many people as possible in his electorate to participate in the postal survey and vote "yes".
But unlike swimming legend Ian Thorpe, he won't be joining a national campaign.
"When it comes to my broader position in terms of campaigning on this issue, I have bigger fish to fry and that is energy policy and that will be my priority in the weeks and the months ahead," Mr Frydenberg told Sky News on Sunday.
It was an issue important to a lot of people but he said it was unclear what sort of response could be expected.
Shadow attorney-general Mark Dreyfus hopes the return is more than 50 per cent.
"It's not going to have much worth if it's only 10 per cent or 15 per cent of people participating," he told ABC TV.
Same-sex marriage advocate Christine Forster hopes with a culture of compulsory voting there will be a solid turnout.
As for the result itself, a 51-49 outcome would leave the country in a "grey area".
The City of Sydney Liberal councillor and sister of former prime minister Tony Abbott hit out at arguments from opponents of same-sex marriage that legalising it would lead to bakers getting in trouble for refusing to make a cake for a gay wedding.
That was just scaremongering, Ms Forster said.
"If the law is changed so that same-sex marriage is legal in this country then people will have to acknowledge that, they will have to accept that if it's the law," she told Sky News.
The postal survey faces two High Court challenges, and Mr Dreyfus believed it was a 50/50 chance it would get the nod of approval.
If the survey returns a "no" vote, the government won't bring a private bill on the matter to parliament.
But Mr Dreyfus insisted Labor, if successful at the next election, would still pursue same-sex marriage.
"It's Labor policy, it's clear Labor policy," he said.
Ms Forster said it would open a "real can of worms" for Labor if there was a resounding "no" vote.
"That's my worst nightmare, is we wake up ... with a strong no vote because both sides of politics, all sides of politics would struggle with that given Australian federal elections are decided on a handful of marginal seats," she said.