Australians support same-sex marriage by a margin of about two to one, today's Essential Report finds, but 40% of voters say it makes no difference to how they'd vote.

Fifty-nine per cent of voters support allowing same-sex marriage, the same level as in February, compared to 55% in December and 60% in June 2014; 30% oppose it, compared to 28% in February and 32% in December. Greens voters support it 93%-3%; Labor 70%-21% and Coalition voters 49%-38%. Women are more strongly in favour of same-sex marriage, 64% to 25%, compared to men -- 54%-34%.