Former prime minister Tony Abbott says he is "confident" about Immigration Minister Peter Dutton's push for a postal ballot on same-sex marriage.

Mr Dutton said the Federal Government should consider a plebiscite by post, saying it could resolve the impasse on same-sex marriage while honouring the Coalition's election commitment.

The Government's bid to hold a "traditional" plebiscite was defeated in the Senate last year, with opponents arguing it would have resulted in harmful debate against the gay and lesbian community.

Labor, the Greens and some Senate crossbenchers want a direct vote in Parliament instead.

Mr Abbott said he was pleased to see Mr Dutton's commitment to letting Australians have their say on the issue.

"I very much respect Peter and I am confident that what he has been trying to do is to secure the best possible way of realising the commitment that we took to the people at the election," Mr Abbott said.

"Now the commitment that was announced under my prime ministership and which I'm pleased to say has been maintained under the current prime ministership, the commitment is that at least for the life of this Parliament, the Marriage Act will not be changed without putting it to the people first."

Mr Abbott would not specifically say whether he supported the idea of a postal vote when asked by reporters in Canberra.

Mr Dutton told radio station 2GB a postal ballot could be a way of honouring the Government's election commitment.

"That's the policy that we took to the last election so I want us to stay true to the policy that we took to the last election and I think ideas should be considered in that context," Mr Dutton said.

"There is this option of a postal plebiscite, which doesn't require legislation as I understand, and it may achieve, in some ways, the same outcome to a plebiscite that you would think of in the traditional sense."