Prime Minister Tony Abbott has thrown an olive branch to supporters of same-sex marriage, announcing the Coalition will look at holding a referendum or plebiscite on same-sex marriage to solve the issue once and for all.

While confirming that the Coalition party room had decided to keep binding MPs on same-sex marriage by a clear majority on Tuesday, Mr Abbott also said that the party had not "finalised a position to take to the next election".

"We have finalised a position for the duration of this term," he told reporters in a snap late-night press conference at Parliament House.

In comments that set same-sex marriage up as a key election battleground next year, Mr Abbott also made a plea to voters who both support and oppose the reform.

"I think I can say arising out of today is that if you support the existing definition of marriage between a man and a woman, the Coalition is absolutely on your side but if you would like to see change at some time in the future, the Coalition is prepared to make that potentially possible," he said.

"But the disposition, as I said, is that it should happen through a people's vote rather than simply through a Parliament's vote."

Reports emerged from the meeting that Foreign Minister Julie Bishop, Treasurer Joe Hockey and Social Services Minister Scott Morrison backed the idea of a plebiscite.

Mr Abbott's press conference came after a marathon five and half-hour party room meeting on Tuesday, called to deal with the same-sex marriage issue.

The surprise tactical manoeuvre - which saw an unscheduled meeting called and Nationals MPs included in the mix - has sparked fury among moderate Liberals.

It also saw several senior ministers break ranks, with Ms Bishop and Communications Minister Malcolm Turnbull criticising the way the debate was conducted.

When asked what he now expected of his frontbench, Mr Abbott sidestepped the question, noting that backbenchers could always vote with their consciences.

"I'm not saying the Coalition's position is set in stone for all time," he added.

Other Coalition MPs saw the result as more emphatic.

Leaving Parliament on Tuesday night, prominent same-sex marriage opponent, Cory Bernardi said he was pleased for the Liberal Party.

"I think it's truly in the national interest this has been resolved tonight and I expect my colleagues will abide by the party policy and we can go forward and focus on the things that are truly important to the people of Australia," he said.

Coalition MP Warren Entsch - who sparked Tuesday's special meeting by raising same-sex marriage in an earlier Liberal Party meeting - said he was disappointed by, but not angry with the outcome.

"In the party room today, during the six hours of discussion, there was potential for highly emotive, over the top debate," he said in a statement.

"However I have to commend my colleagues for the robust and respectful standard of the conversation, notwithstanding the fact that there were diametrically opposed views."

Mr Entsch confirmed that he would still introduce his cross-party bill to legalise same-sex marriage next Monday, but conceded that it would now fail without a free vote for Coalition MPs.

- with Mark Kenny