Conservative MPs fight calls within Coalition to endorse marriage equality

Conservative Coalition MPs have resisted a push within their own party to back the same-sex marriage bills before parliament.

Assistant Treasurer Josh Frydenberg became the most recent government minister to publically declare his support for same-sex marriage on the ABC’s Q&A program last night.

The move earned a stinging rebuke from ACT Senator Zed Seselja, who called on his colleagues to tow the party line on the policy.

"I'm not going to target any one individual but we did see comments last night on Q&A and I don't think that's helpful," Mr Seselja said.

"I don't think we should have a situation where ministers go against party policy.

"We do have a very long-standing position on this, and I believe that the vast majority of our supporters support that."

Mr Seselja's comments were echoed by outspoken South Australian Senator Cory Bernardi.

"Somehow we've now got a circumstance where we've got frontbenchers who are prepared to undermine the current position and they get away with it," he said.

"It's quite extraordinary."

The comments came despite the fact Prime Minister Tony Abbott, himself an opponent to same-sex marriage, has previously acknowledged MPs were allowed to disagree on the issue.

Last night, Mr Frydenberg said he would vote in favour of same-sex marriage if he was given a free choice to do and said marriage equality was "inevitable" in Australia.

"I, like many of the other local members in the parliament have met with a number of constituents and my views have evolved after meeting with constituents and seeing the deep affection that people of same-sex relationships have for each other," he said.

He joined Communications Minister Malcolm Turnbull, Environment Minister Greg Hunt and a host of Coalition backbenchers to endorse a change to the Marriage Act.

There are currently three bills before parliament calling for marriage equality.

Opposition Leader Bill Shorten introduced his private members bill yesterday, which followed earlier legislation proposals by the Greens and Liberal Democrats Senator David Leyonhjelm.

Liberal MP Warren Entsch is also working on a bi-partisan bill, set to be introduced before the end of the year.