A Labor backbencher's bid to legalise gay marriage in South Australia has been defeated in the state's lower house.
Susan Close's bill was defeated on Thursday after Liberal MPs opposed it on party lines, while Labor members were given a conscience vote.
Premier Jay Weatherill supported the legislation, having previously said he wants the state to be a trailblazer.
Opposition Leader Steven Marshall said his party considered the bill unconstitutional but will reconsider its stance if more evidence came to light.
Australian Marriage Equality national director, Rodney Croome, said advocates remained hopeful that same-sex couples will be able to legally marry in SA despite Thursday's vote.
"There is another bill before the state upper house which we believe has a good chance of being passed if and when the Liberal Party allows a conscience vote," he said in a statement.
"We will continue to campaign for marriage equality in South Australia, addressing the constitutional and social concerns raised in today's debate.
"Our focus will be on introducing MPs to those South Australian couples and their families who urgently need this reform and who don't have time to wait for the federal parliament to act."