Legalizing same-sex marriage may take years in Australia now that government leaders have officially declined a national referendum, which would have taken place in February 2017.

Opposition leader Bill Shorten appeared in a press conference today to confirm the Labor party had rejected the plan, citing the "overwhelming harm it may cause."

Such harm, according to Shorten, includes the $120 million cost to hold a plebiscite, and the stress a national debate on such a divisive issue may cause to families, children, and LGBT people who might be subjected to hateful rhetoric.

"I could not look at these loving families and parents of gay people, people in committed same-sex relationships, young people whose parents are gay, and say to them that this plebiscite was good for them," said Shorten.

"This country does not have the right in a plebiscite to pass judgement on the marriage and relationships of some of our fellow Australians."

Instead Shorten lobbied for Parliament to vote on the matter.

Critics of a Parliament vote on same-sex marriage, including Prime Minister Malcolm Turnbull, argue that it could delay marriage equality legislation until at least 2019 because Parliament simply doesn't have enough votes to support it.