Australian Prime Minister Malcolm Turnbull introduced a bill that would allow people to vote on whether same-sex marriage should be legalized. The vote would not be binding. (Rob Griffith/AP)

As the Australian Parliament weighs whether to hold a countrywide vote on marriage equality, the plebiscite's loudest critics have been LGBT advocates themselves.

Prime Minister Malcolm Turnbull introduced a bill Wednesday that would allow all adult Australians to vote on whether same-sex marriage should be legalized. The vote would not be legally binding, but it is intended to serve as a guide for Parliament's future actions on the issue.

Several LGBT groups oppose the vote. They caution that public debate on same-sex marriage would legitimize discriminatory views, giving bigots a wider platform for spreading homophobia. The organizations think the discussion should be left to lawmakers.

"The idea that any group of people would have their relationships measured and discussed and have people talk about whether they have a value at all to society — there's no way to conceive that wouldn't be a difficult journey," Tiernan Brady, director of Australian Marriage Equality, told CNN.

Another point of contention has been the steep price tag. In the lead-up to the vote scheduled for February, both sides — for and against same-sex marriage — will each be given about $5.6 million to publicize their perspectives.

Turnbull, who supports marriage equality, told Parliament that the plebiscite's critics think reform could have been pushed forward without hearing from voters.

“They don't want to run the risk of the Australian people giving them the wrong answer,” he said, according to the Associated Press. “For our part, we put our faith in the Australian people and we know that their answer, whether it is 'yes' or 'no,' will be the right answer.″

Earlier this week, a senator in Turnbull's Liberal Party made the rare decision to go against party lines.

In a column for the Sydney Morning Herald, Dean Smith outlined his position:

As the first openly gay Liberal to serve in federal Parliament, speculation about my motivation on the issue is to be expected.

I am well aware that no explanation on my part will be enough to placate those critics who, disappointingly and dishonestly, wish to portray this as ‘the gay Senator campaigning for gay marriage.’

The question of whether to have a plebiscite, Smith wrote, was not just about same-sex marriage. It also tested “the foundational principle of Australia's parliamentary democracy.″

He continued: “In an age where public respect for the institution of parliament is already at a low ebb, we can ill afford to further undermine public confidence by effectively admitting that our federal Parliament can no longer deal with the big questions.”

Plebiscites, which differ from referendums in that their results need not be rendered law, have only been held three times in Australian history. Two concerned conscription during World War I, and the third was about the national anthem.

Smith worried that a same-sex marriage plebiscite would set the precedent for other votes around contentious issues, such as euthanasia and abortion, further pushing Parliament to the sidelines.

The bill hinges on the support of the opposition Labour Party, which has hinted that it will block the plebiscite, CNN reported.

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