The Liberal Democrat senator David Leyonhjelm will push ahead with plans to introduce a bill to allow same-sex marriage, warning he could withhold his crucial crossbench vote on other legislation to pressure the government to allow a conscience vote.



Leyonhjelm said his bill, to be presented to the Senate by September, would “deregulate” marriage by allowing Australian couples to marry regardless of gender. He portrayed the case for same-sex marriage as a libertarian issue of small government, saying many Liberals supported his position and should be allowed to vote according to their conscience.

The comments came a day after the Australian swimming legend Ian Thorpe revealed he was gay in a television interview recalling his struggles with depression and identity.

Australians were ready for same-sex marriage, Leyonhjelm said, stressing that it should be a matter for individuals to decide rather than the government.

The New South Wales senator dismissed any suggestion of a left-right divide on the issue.

“It’s coming from a straight, middle-aged, conservative man who’s saying you don’t have to approve. All you have to do is respect the fact that it’s not the government's business. That’s the point I want to get across.”

When the previous parliament voted down same-sex marriage, Coalition members were bound to vote against the legislation rather than being afforded a conscience vote, as Labor members were. Tony Abbott has not ruled out a conscience vote in this term, saying the Coalition party room would consider its position on any marriage bill if and when it was presented to parliament.

Leyonhjelm, one of eight crossbench senators who are crucial in deciding the fate of any government legislation opposed by Labor and the Greens, said he would consider making his support for another government policy conditional on a conscience vote being granted to senators and MPs.

“I don’t want anybody to vote against their conscience,” he said.

“If I have to use my leverage to ensure there is a conscience vote then, if necessary, I will. I’m hoping I can win them over by persuasion because there are many people in the Liberal party who agree with me on this.”

Leyonhjelm nominated government legislation to allow temporary protection visas for refugees as an area in which he could threaten to withhold his support.

“I don’t care either way whether that goes through or not because I think the government’s immigration model – and that includes Labor’s immigration model from the previous government – is long term unsustainable,” he said. “I think our model is better, so therefore the temporary protection visa issue is neither here nor there to me. So if the government wants my support there is going to have to be a contra.”

Leyonhjelm challenged politicians who professed to be in parliament to make a difference to prove it by backing his same-sex marriage bill, saying it was not the job of governments to define relationships. In future people would “look back on the role of governments to grant marriage certificates based on gender as the bizarre misappropriation of power that it is”.

But Leyonhjelm’s bill would stop short of abolishing marriage legislation entirely. Instead, it would remove the requirement that marriage be between a man and a woman, and would also ensure marriage celebrants were free to preside over whatever marriages they chose.

“Today, I challenge Mr Shorten and Labor party members to look senator [Penny] Wong in the eye and tell her she does not deserve equal rights,” he said. “Today, I challenge prime minister Abbott and Liberal party members to do the same with Mr Abbott’s sister [Christine Forster].”

The deputy Labor leader, Tanya Plibersek, has also previously flagged introducing a private member's bill once she was confident Liberal MPs would be allowed a conscience vote.

Ivan Hinton, spokesman for the Australian Marriage Equality lobby group, said Leyonhjelm’s bill was exciting because it demonstrated broad political support for marriage equality for various reasons.

“He’s specifically focused on the rights of individuals to live their lives without the government intervening unnecessarily,” Hinton said. “His philosophy is critical of the idea that the government can intervene in some people’s lives and say you’re not entitled to a civil institution [marriage] based on your sexual orientation.”

Hinton said Thorpe “puts another face to the discrimination that still exists in our community”.

“He clearly struggled for years to come to terms with his sexuality and you can’t deny that institutional prejudice, like the current Marriage Act, doesn’t have an influence in people’s fear of coming out,” Hinton said.

Abbott has repeatedly affirmed his opposition to same-sex marriage, but said the party room would consider its stance if a private member’s bill came before parliament.

“Our policy has been that marriage is between a man and a woman, but in the end it’s up to the party room to decide what our policy is,” the prime minister told the ABC in December.

The communications minister, Malcolm Turnbull, a strong advocate for change, said in December he thought it was “very likely” that the parliament would consider a private member’s bill and that the Coalition party room would agree to a conscience vote.

In December the high court struck down the nation’s first same-sex marriage laws, introduced by the ACT government. The court found, however, that the federal parliament had the constitutional power to introduce a national law allowing same-sex couples to marry.