Conservative senators are warding off a renewed push for a free vote on same-sex marriage for Liberal MPs, warning it would lead to chaos and fail anyway in the party room.
But prominent Liberal MP Alex Hawke, who does not support same-sex marriage, is calling for a conscience vote, saying a showdown is the "only way" to resolve the issue.
Liberal MPs will need to make a decision on same-sex marriage in the new year, with Liberal Democratic Party senator David Leyonhjelm introducing his marriage equality bill to the Senate on Wednesday evening.
Prime Minister Tony Abbott - who is a strong opponent of same-sex marriage - has repeatedly said that the issue of a free vote on the matter would be a matter for the post-2013 election Liberal Party room.
Senator Leyonhjelm said that Mr Abbott was "not enthusiastic" about the prospect of the debate, telling the DLP Senator the government had enough troubles at the moment during a recent dinner.
Senator Leyonhjelm's bill provides the catalyst for a Liberal party room decision as it requires a bill to be before Parliament to prompt debate on the issue. Liberal Senators Cory Bernardi and Zed Seselja warned against a free vote, arguing the party's policy was not up for debate.
"The Liberal Party has respected the institution of marriage as being between a man and a woman since its establishment. The demands that we should abandon this position would undermine the foundation of the party itself," Senator Bernardi said.
"It's not a matter of life or death and to grant a conscience vote on marriage would be open every policy of the Liberal Party to some sort of voting free for all."
Senator Seselja said the party should still have a position on "something as important as marriage". He said he did not support a free vote and "that is a view shared by the majority of my colleagues".
Marriage equality advocates believe they have the support of up to 70 per cent of the party room for a conscience vote. But other Liberal sources say it is impossible to estimate the numbers at this stage.
Mr Hawke is calling on Mr Abbott to come out and declare a free vote on the matter, rather than the party room having to vote to get there.
"I think that's the strongest position to take [for] any leader," he said.
Mr Hawke said that he strongly supported a free vote, explaining, "at the end of the day, it's the only way to resolve these things".
He argued that the debate needed to be about the substance of the same-sex marriage issue, not on whether there should be a debate about it.
"I don't think anyone [on the side against changes] has got anything to hide."
Mr Abbott's sister, City of Sydney councillor Christine Forster, said she would "really like" to see a free vote in the federal Liberal party room
Councillor Forster, who is engaged to marry her partner Virginia Edwards once same-sex marriage is legal federally or in NSW, said that MPs on both sides of Parliament were not standing up on the issue because they were not "getting the right signals" from their electorates.
She said same-sex marriage supporters in all electorates should "make their views known" to MPs.
