Tony Abbott has declared that Coalition frontbenchers who break rank and vote in favour of gay marriage will be sacked.

The Prime Minister was responding to a potential vote on the legalisation of same-sex marriage, if MP Warren Entsch were to successfully introduce a cross-party bill to parliament this morning.

“It is ... the standard position of our party that if a frontbencher cannot support the party’s policy, that person has to leave the frontbench,” Mr Abbott told ABC radio this morning.

Last night the Coalition has ruled out whether to have a conscience vote regarding the legalisation of same-sex marriage.

Following a meeting lasting almost six hours, the Coalition party room, made up of Liberal and National MPs, voted 66 to 33 against having a free vote on marriage equality.

“Obviously our backbenchers are entitled to vote in the end, whichever way they want,” said Mr Abbott.

“I would be disappointed if they went against the party position but nevertheless we have always accepted that in the end all votes in our party room for backbenchers at least are conscience votes.”

Mr Abbott said he accepts people may be disappointed over the Coalition's decision to reject a free vote on same-sex marriage but says the government has to keep faith with the public.

"There is the prospect of change in the next parliament if that is the will of the Australian people," Mr Abbott told ABC radio, referring to a proposal for a national plebiscite.

The prime minister said it was only the current generation that had thought of gay marriage so "why not give it to the people?"

The prime minister recalled university debates with gay friends.