Voters in some of the most conservative seats in Australia overwhelmingly support legalising same-sex marriage in 2017, according to a decisive new poll of a dozen Coalition seats.

And Coalition MPs are seen as out of touch with the community – and could lose votes, and even their seats – if they continue to block a free vote in Parliament and insist on the defeated plebiscite policy.

The ReachTel poll of 12 Coalition seats, commissioned by Australians for Equality, targeted Bowman, Brisbane, Cook, Fisher, Goldstein, Moncrieff, New England, Pearce, Petrie, Robertson, Swan and North Sydney. Its findings are in line with a February ReachTEL poll of seven Coalition seats.

More than 50 per cent of voters in all 12 seats said "yes" when asked if same-sex couples should be allowed to marry. A majority of voters in all 12 seats also said it was "very important" that the issue was resolved by parliamentary vote in 2017.