The Federal Government will hold a plebiscite on same-sex marriage by the end of the year, if re-elected.

Attorney-General George Brandis confirmed the timing for the public vote today, but said the bill for the plebiscite would not be made public before the federal election.

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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 this was a conscience matter and I haven’t changed my mind,” he said.

Di Natale said the public vote would give a voice to “groups who spread bigotry”.

“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.”

The potential plebiscite — expected to cost up to $160 million — has been a matter of concern for some politicians, who fear the campaign could turn vitriolic.

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.