The Australian Labor Party says it'll block the government's plans to hold a nationwide vote on marriage equality, saying parliament should make the call.
Australian Prime Minister Malcolm Turnbull has pledged a non-binding ballot, or plebiscite, in February 2017.
However, critics of the plan say it will do nothing but sow fear and divisiveness across the country.
Parliament still has to vote on whether to hold the plebiscite, but without Opposition support it is unlikely to pass the senate.
Labor leader Bill Shorten says a nationwide plebiscite could be a "lightning rod for the very worst prejudice so many LGBTI Australians endure".
Mr Shorten called for a free vote in parliament, where the issue could be decided in one day following "considered debate".
"A free vote on marriage equality means we could be attending the spring weddings of people who have waited long enough. A free vote is the cheapest, fastest and the least harmful way.
"Let's just get on with it, let's make marriage equality a reality," he says.
Mr Turnbull hasn't ruled out a free vote on same-sex marriage, but the party was determined to go on with a plebiscite.
Recent polls show marriage equality has the backing of the majority of Australians, with an Essential poll from October 5 showing 58 percent would vote 'yes' in a plebiscite, with 28 percent ticking 'no', while the rest didn't know.
When asked, 53 percent said they'd prefer the Liberal/National government agree to a vote in parliament, while 24 percent said Labor and other parties should agree to a plebiscite.