Senior Liberal MP Malcolm Turnbull says it is ‘‘likely’’ the Coalition government will allow a conscience vote on gay marriage before the next election, but it is too soon to say if it will be successful.

After the High Court’s decision to strike down ACT same-sex marriage laws, attention has now shifted back to federal parliament.

Legislation to allow gay marriage was voted down in the last parliament, with then opposition leader Tony Abbott refusing to allow his party a conscience vote.

But Mr Turnbull, a supporter of gay marriage, says that could if change if the issue is revisited in the next three years.

‘‘I think it is likely that we will (have a free vote), but as Tony Abbott has said, it is a decision for the party room, not for him,’’ he told Sky News on Sunday.