Federal Liberal MPs have overwhelmingly decided to keep their current policy on same-sex marriage.

Key points: Seven Liberals voted to change the same-sex marriage policy

Seven Liberals voted to change the same-sex marriage policy The push by a small group of Liberals for an immediate conscience vote has failed

The push by a small group of Liberals for an immediate conscience vote has failed Finance Minister Mathias Cormann hopes the bill will be returned to the Senate this week

Only seven Liberals voted to change the policy after a two-hour meeting ended with a show of hands.

The seven MPs who voted to change the policy were: Warren Entsch and Trevor Evans (Qld), Tim Wilson and Jason Wood (Vic), John Alexander and Trent Zimmerman (NSW) and Senator Dean Smith (WA).

It means the push by a small group of Liberals for an immediate conscience vote on same-sex marriage has failed.

The MPs who voted yes: 1. Warren Entsch (Qld) 2. Trevor Evans (Qld) 3. Tim Wilson (Vic) 4. Jason Wood (Vic) 5. Dean Smith (WA senator) 6. John Alexander (NSW) 7. Trent Zimmerman (NSW)

But Mr Wood said it was "great news" because Australia had come a step closer to having same-sex marriage.

The Coalition will now try again to have a plebiscite — or national vote — on whether the law should be changed to allow same-sex marriage.

Mr Wood said he strongly believed Australians would vote in favour of same-sex marriage.

And he said the feedback in his electorate was that people he represented would also vote for allowing same-sex marriage.

But Mr Entsch said he was disappointed and was reserving his right to cross the floor on same-sex marriage, despite the outcome of today's partyroom meeting.

He said he could still introduce a private member's bill into Parliament.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 6 minutes 27 seconds 6 m Warren Entsch on his fight for same-sex marriage ( Leigh Sales )

Finance Minister Mathias Cormann said he hoped the bill for a plebiscite would be returned to the Senate this week.

He said it would be for a compulsory vote and if a majority of Australians supported same-sex marriage then Coalition MPs would subsequently get a conscience vote in Parliament.

"Well, the position of the Government is that if the plebiscite vote comes back with a 'yes' vote in favour of changing the law to allow same-sex couples to marry, we will have a private member's bill to change the law," Senator Cormann said after the meeting.

"There would be a free vote informed by the plebiscite outcome and our expectation would be that that law would pass the Parliament."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 11 minutes 29 seconds 11 m Mathias Cormann tells Emma Alberici sticking to the plebiscite policy is not just a political fix

Opposition Leader Bill Shorten issued a statement shortly after the Liberals' partyroom meeting, saying he was "disappointed" for thousands of Australians who had been "let down" by Prime Minister Malcolm Turnbull.

"The Liberals have spent yet another day arguing over whether or not gay and lesbian Australians should have their relationships judged by everyone else," he said.

"Another day spent fighting with each other over an issue that we could sort out in five minutes if Mr Turnbull would just let the Parliament do its job and vote on it."

Sorry, this video has expired Political editor Chris Uhlmann on the Liberal Party vote

Plebiscite likely to hit same roadblock

But it looks likely the Senate will again reject the bill for a plebiscite, as it did last year.

Senator Xenophon indicated he would again refuse to support a plebiscite, saying: "It was like groundhog day. And it's going to keep happening over and over again until people make a decision and let the Parliament vote on it."

Last November, the legislation to set up a plebiscite failed in the Senate when Labor, the Greens, the Xenophon Team and Derryn Hinch combined to reject it.

Coalition senators, One Nation, Jacquie Lambie and David Leyonhjelm voted for it but their backing was not enough for the plebiscite bill to pass.

Campaigners for same-sex marriage are confident that if both sides of Parliament allow a conscience vote, then the law would be changed.

Federal Labor has a conscience vote during this term of Parliament but its members would be bound to vote for same-sex marriage after the next election.

The Coalition has traditionally allowed its members to have a free vote, but so far in this term of Parliament it has insisted that it should stick to the policy of having a plebiscite and has resisted any push for a vote on the marriage act.