Same-sex marriage is likely to be delayed for at least three years in Australia after the opposition Labor party said on Tuesday it would not support a national vote.
The move deals another potential blow to Prime Minister Malcolm Turnbull.
Australia's centre-right coalition government introduced legislation to parliament last month to hold a public vote in February 2017 on whether to legalise same-sex unions.
The bill required the support of some opposition lawmakers because Turnbull's Liberal-National coalition has only a one-vote majority in the lower house of parliament and does not have a majority in the upper house.
The rejection is a blow to Turnbull, who has seen his popularity wane amid frustration that he has failed to live up to his progressive reputation.
Same-sex marriage is supported by 61 per cent of Australians, a Gallup poll in August found.
Several independent MPs had already ruled out supporting the national plebiscite on same-sex marriage. The rejection by the centre-left Labor party, which wants same-sex marriages legalised by parliament, ended any hope the plebiscite bill could pass.
"Why should gay Australians be subjected to a different law-making process than any other Australians?" said Labor leader Bill Shorten.
"Why should a couple in a committed relationship have to knock on the doors of 15 million of their fellow Australians and see if they agree with it? The easiest way is the way which this parliament has done for a hundred years – legislate."
Advocates of same-sex marriage who oppose a referendum are also concerned public debate around the vote would prove harmful, sparking homophobic rhetoric against same-sex unions.
Those who oppose it are also critical. The Australian Christian Lobby, which campaigns against gay marriage, said it was disappointed by parliament's decision. Managing director Lyle Shelton said: "Despite constantly claiming overwhelming public support for redefining marriage, it is perplexing that advocates are not willing to trust the Australian people with a decision that has enormous consequences for all families.
"Such a big change with such big consequences for what children are taught at school, the rights of children to know their mother and father and for freedom of speech should be taken to the people."
Additional reporting by Reuters.
