The Greens have slammed the same-sex marriage plebiscite as a "farce", after it was revealed on Saturday a loophole may allow conservative MPs and senators to ignore the national poll and vote in favour of their individual electorate's view.
The plebiscite has already been criticised as an exercise costing millions of taxpayer funds which may not achieve any legislative change. It also threatens the mental health of children with same-sex parents by increasing hate speech in the public domain.
Greens marriage equality spokesperson Robert Simms said the plebiscite is an "expensive sham and farce".
"Yesterday we were told it won't be binding and today we learn the Liberals are deliberately setting it up to fail," Senator Simms said in a statement.
"LGBTI Australians shouldn't be used as pawns in Prime Minister Malcolm Turnbull's desperate attempts to hold onto his job. Poll after poll shows Australians want marriage equality.
"The Greens want to make marriage equality a reality through a vote in the parliament. It's not too late for Mr Turnbull to show some backbone and dump this plebiscite con."
The Greens aren't the only party in favour of a vote in Parliament. Labor leader Bill Shorten is spruiking same-sex marriage would be passed in Parliament within the first 100 days if he were elected.
Malcolm Turnbull has previously said both he and wife Lucy are in favour of marriage equality but his Cabinet-first leadership style will enforce a plebiscite after the election. Putting the party view first has been a constant in Turnbull's election campaign.
On Saturday morning Fairfax revealed there was a "secret push" within the Coalition to allow conservative MPs and senators to vote against marriage equality if their individual electorates had voted 'no' -- even if the national vote was in favour of same-sex marriage.
Fairfax reports backroom tensions between Attorney-General George Brandis -- who is in favour of same sex marriage -- and conservative MPs over a free vote.
On Friday night Prime Minister Malcolm Turnbull said "tradition in the Liberal Party is that on matters of this kind, it is a free vote".
"I have no doubt that if the plebiscite is carried out, as I believe it will be, that you will see an overwhelming majority of MPs and senators voting for it," Turnbull said.
The Prime Minister said Treasurer Scott Morrison is one conservative minister who will vote in favour of same-sex marriage if the national vote is in favour of marriage equality.