The Prime Minister's office has refused to back an end-of-year deadline for a plebiscite for same-sex marriage.

Key points: Question will be made public ahead of plebiscite

Question will be made public ahead of plebiscite Labor pledges to call for vote on same-sex marriage within 100 days if elected

Labor pledges to call for vote on same-sex marriage within 100 days if elected Richard Di Natale says public vote will give voice to "groups who spread bigotry"

Attorney-General George Brandis unveiled the timing for the public vote this morning, adding it would be legislated by the end of the year if the public voted in favour of change.

But the timeframe was not backed by Prime Minister Malcolm Turnbull when contacted by the ABC on Sunday.

A spokesperson for the Prime Minister's office said the Government will hold the plebiscite as soon as possible after the election, but could not say whether that would be by the end of the year.

Senator Brandis told Sky News he believed the plebiscite would be carried, meaning that if the public voted yes, Parliament would follow.

But he said it would be understandable if some politicians maintained their stance against the change.

"I've said in the party room when this matter was discussed last August that I thought this was a conscience matter and I haven't changed my mind," he said.

"[But] I think it would be perfectly understandable why a member of Parliament representing a conserve electorate and having conservative views themselves might choose to vote no. And I don't have a problem with that."

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Labor has pledged to call for a vote on same-sex marriage within 100 days if elected, but Senator Brandis said he was not concerned about the commitment.

Senator Brandis said the question would be made public ahead of the plebiscite, but would not confirm if it would be spelt out ahead of the election campaign.

He said that personally, he was in favour of same-sex marriage.

"This is a position I've come to over the years and after a lot of reflection," he said.

"I believe that marriage is one of the fundamental institutions of society and I think it's important the fundamental institutions of society reflect the fundamental values of society.

"Treating gay people equally is, I think, one of the fundamental values of modern, Australian society."

Vote could 'rip the bandaid off' unpleasant views

Opposition Leader Bill Shorten said the Coalition could settle the issue with a vote in Parliament during the next sitting period.

Mr Shorten said on Sunday that the plebiscite was "an idea created by the opponents of marriage equality to kick marriage equality down the road".

"Our objections to the plebiscite aren't just that it's a delaying tactic designed by the opponents to marriage equality," he said.

"The Liberal Party said that they're not going to be bound by the result. So why is it that we're having a plebiscite put forward by the Government which individual Liberal MPs said they're not going to be bound by anyway?

"It's just a very expensive opinion poll."

Mr Shorten also voiced concerns that a plebiscite campaign could "rip the bandaid off" unpleasant views held by some in society.

Greens leader Richard Di Natale voiced similar concerns, saying the public vote would be divisive and give a voice to "groups who spread bigotry".

Senator Di Natale told the ABC today that the vote would "cause so much damage".

"I think the big problem for Malcolm Turnbull right now is that while there's been a change in Prime Minister, he's carrying on with Abbott era policies," he said.

Senator Di Natale also referred to the debate over the Safe Schools program, which has prompted heated commentary from both politicians and the public.