All Australians eligible to vote are currently being asked to respond to the question "Should the law be changed to allow same-sex couples to marry?" in a national survey.

Prime minister Malcolm Turnbull and Labor leader Bill Shorten are on a unity ticket when it comes to same-sex marriage itself, despite disagreeing on the postal survey.

And across Australia, state and territory premiers, chief ministers and opposition leaders have all said they will vote "yes" in the survey — except for Coe, who is voting "no".

Coe, who is in his early thirties, became the leader of the ACT Liberals last October, following the party's loss in the 2016 election. He is from the conservative wing of the party and was backed for the leadership by federal ACT senator Zed Seselja.

Coe was unavailable for an interview with BuzzFeed News, but provided a statement: "I, along with many other Canberrans and Australians, will be voting no."

"Of course, a robust democracy is built on the back of many voices engaging in debate and all Australians, regardless of their views, culture, ethnicity, faith or sexuality should enjoy the democratic freedom to exercise their conviction in this survey.