But Ms Plibersek will only introduce the bill to Parliament if Prime Minister Tony Abbott allows his MPs a conscience vote on the issue. If Mr Abbott does not do so, introducing the legislation would be nothing more than symbolic, as Labor and any crossbench supporters would be trounced on the floor of the House of Representatives. Mr Abbott's office said on Tuesday that his position remains that if a same-sex marriage bill comes before Parliament it will be a matter for the Coalition party room. Unlike their Labor counterparts, Liberal MPs do not have a conscience vote on the matter, but Mr Abbott has left open the possibility of a free vote, saying the issue was a matter for the post-election party room. "Liberal MPs pride themselves on being able to cross the floor on issues," Ms Plibersek said. "Tony Abbott needs to confirm that includes marriage equality." Ms Plibersek is looking for a Liberal co-sponsor for the bill, and her first choice is Coalition frontbencher Malcolm Turnbull, who has publicly declared his support for same-sex marriage.

But Mr Turnbull will not be co-sponsoring the private member's bill as he is a cabinet minister and it would be in breach of protocol. Mr Turnbull has made his position clear: he would only vote for same-sex marriage if Mr Abbott allowed a conscience vote in the Coalition partyroom. Greens Deputy Leader Adam Bandt said while the Greens were ready to co-sponsor a new marriage equality bill he has written to Ms Plibersek asking her to allow the cross-party committee to reach a consensus before proceeding with a bill. "Labor rushed its bill to a vote before the last election before work was done to get Liberal backbenchers on board," Mr Bandt said. "We don't want that to happen again."We all need to work together if we are going to achieve equality." As Fairfax Media reported last December, same-sex marriage advocates have drawn up a hit list of about 70 federal politicians, including Foreign Minister Julie Bishop and Treasurer Joe Hockey, who they think could be persuaded to change their position on same-sex marriage. But they have an uphill battle ahead of them, with a Fairfax Media survey of 15 new Liberal MPs revealing none were willing or able to declare their support for same-sex marriage.

This comes after the High Court found in late 2013 that ACT same-sex marriages were not legal, but that it was possible for the federal Marriage Act to be changed to allow for same-sex marriages. If Liberal MPs were given a conscience vote, about 25 MPs would need to change their position in the House of Representatives to pass same-sex marriage legislation, according to Australian Marriage Equality national director Rodney Croome. In the upper house, about 10 senators would need to change their minds, he said. But despite recent publicity of same-sex marriage at both the state and federal level, the issue remains on the back burner within Coalition ranks in Canberra. It is understood same-sex marriage has not been raised in Liberal party room meetings since the September election. A Fairfax Media survey of more than 20 new Liberal MPs also found that of the 15 who responded, none indicated outright that they supported same-sex marriage. Five MPs indicated they had no firm position or would consult their electorates about their position, in the event of a vote.

On the Labor side of the Federal Parliament, marriage equality advocates are buoyed by the new Labor leadership team, which for the first time, includes a leader and deputy leader who support same-sex marriage. Follow us on Twitter