Attorney-General George Brandis has said the government will be open to compromising with Labor on the structure of the same-sex marriage plebiscite, if it means getting the vote through Parliament.

His comments come just two days after Malcolm Turnbull also spoke of the need to negotiate on issues, given the make-up of the 45th Parliament, where neither major party holds a majority in the Senate.

While a spokeswoman for Mr Turnbull clarified after the Prime Minister spoke that there would be no changes to the plebiscite policy, its question or the $15 million in public funding for the yes and no campaigns, Senator Brandis told Sky News on Sunday that “the byword of the 45th Parliament is compromise”.

“We have a package which was developed after very, very extensive consultation with people who both favour change in the LGBTI community and people who are opposed to change, particularly among the Christian churches,” he said

“That said, of course the theme of this Parliament has to be compromise.

“We have to deal with the Parliament that the people gave us and that means, of course, a Parliament where the government has only 30 of the 76 seats in the Senate.”

The Greens and the Nick Xenophon Team have said they would prefer to see the matter decided through a vote in Parliament, rather than a plebiscite. Labor has given every indication it will not support the plebiscite in its current form, but is yet to take a formal stance.

While Senator Brandis conceded the plebiscite was “constitutionally unorthodox” and “outliers” on both sides of the argument would not engage in civil debate, he said that was not reason enough not to have the debate.

“I don’t think that we should regard it as a done deal – this is still an argument that has to be made, it’s an argument that has to be made during the plebiscite campaign, but that said, I am very confident that the yes vote will pass …”

However, shadow attorney-general Mark Dreyfus reiterated Labor’s stance that the government should instead back the proposal for a free vote on the issue in Parliament, seemingly leaving the government little room with which to negotiate.

“Perhaps some more honesty could be displayed by Senator Brandis. He could admit that the only reason this plebiscite is being proposed is because supporters of marriage equality like him and Mr Turnbull do not have the backbone to stand up to their backbench,” he said in a statement.

“He could admit that the pretence that a plebiscite is the only way marriage equality can be achieved in this country is completely false, and that the plebiscite is the last great hope of opponents to defeat the cause of marriage equality for good.

“We could have marriage equality in Australia on the first day of the next sitting week of Parliament if Mr Turnbull and Senator Brandis wanted it. It is the government that is holding back the cause of marriage equality.”

Senator Brandis would not say what aspects of the plebiscite the government was prepared to budge on. But he said that as shown by negotiations on the government’s omnibus budget savings bill, which resulted in tweaked legislation that gained Labor’s support, there was room for compromise.

“It is not good enough to just lay down the law to the Senate and say take it or leave it; that is not the way the system works,” he said. Parliament will resume in three weeks.