A poll indicating most Liberal voters support a conscience vote on same-sex marriage is reason enough for Tony Abbott to allow one, advocates say.
The Galaxy poll, published in the Sunday Herald Sun, found 77 per cent of Coalition voters support a conscience vote on the issue.
Results show the majority of Australians are also in favour of marriage equality, with only a third of voters against the reform.
"By allowing a conscience vote, Tony Abbott will represent the wishes of Coalition voters, prevent disunity in Coalition ranks, and be seen as upholding Coalition values of individual freedom," Australian Marriage Equality national convener Alex Greenwich said in a statement on Sunday.
Mr Greenwich said it was the first time in the party's history that Liberal MPs had not been granted a conscience vote on a substantive policy issue when Labor MPs were granted one.
"The Liberal Party prides itself on allowing more freedom to their MPs than the Labor Party does, but on this issue Tony Abbott is turning his back on party tradition and liberal values," he said.
Coalition figures who reportedly support a conscience vote include Joe Hockey, George Brandis, Christopher Pyne, Greg Hunt, Senator Nigel Scullion, Malcolm Turnbull, Barry O'Farrell, Simon Birmingham, Barnaby Joyce, Russell Broadbent, and former Howard Government minister, Amanda Vanstone.