The government will release the proposed amendments to the Marriage Act that will constitute a plebiscite on same-sex marriage in the coming months, Attorney-General George Brandis has indicated.

Crikey reported yesterday that before a plebiscite on whether to allow same-sex couples to marry can take place, the government will need to pass legislation to allow the plebiscite. If the Greens and Labor remain opposed to the plebiscite and vote it down, the government will need to win over crossbench senators in order to set up the plebiscite. Motoring Enthusiast Party Senator Ricky Muir has already indicated he is not in favour of a plebiscite.

Brandis confirmed that the government would need to legislate for a plebiscite at Senate estimates last night. He said either he (with responsibility for the Marriage Act) or Mathias Cormann as acting special minister of state (in the absence of Mal Brough) would bring the legislation soon.

Brandis is considering options to take to cabinet “in the coming months”, including the option for having a self-executing plebiscite. That would mean the Marriage Act would be amended now to allow same-sex couples to marry, but the change would only come into effect if voters approve the change at the plebiscite, thus avoiding a situation where opponents such as Eric Abetz and Cory Bernardi ignore the will of the people and still vote against the change.

The Attorney-General did note, however, that there might be potential constitutional issues with this model. Brandis said he wanted to released the proposed changes to the Marriage Act and then ask in the plebiscite whether voters supported the change (this could be the model whether the plebiscite was self-executing or not).

Brandis said he had been engaging with groups both in favour of and opposed to the change, but he had yet to decide whether public funds would be provided to both sides to make their case. Community groups have warned that any such funding would lead to taxpayer funds being spent to demonise gay people by groups such as Marriage Alliance, which was recently criticised for a photoshopped image of a rainbow noose on a woman.

No costing had yet been done on the plebiscite — outside the Australian Electoral Commission’s $160 million estimate — and Brandis said that the funding would likely be included in the 2016-17 budget. He acknowledged it was much more expensive than Parliament having a free vote on the matter, but said it was important due to the “very strong feelings” on both sides of the debate:

“It is not controversial that having a plebiscite will cost a lot more money than dealing with the issue in parliament … what you have to factor in is the value of having this issue resolved by the Australian people in a thoroughly democratic matter, and I don’t think it is very easy to put a financial price on the benefit of doing that.”