Australians aged 18 to 34 are effectively split on whether the Turnbull government should hold a postal vote on same-sex marriage.
The latest Essential poll, published on Tuesday, shows 43 per cent of voters in that age bracket approve of the decision to hold a survey via the post.
But 42 per cent disapprove.
Across the board, 47 per cent of those surveyed disagree with going down the path of a postal ballot after the Senate twice rejected holding a plebiscite on the issue, compared to 39 per cent in favour.
More than half (56 per cent) of those in the 55 and over age bracket disapprove of the postal plan.
Only 49 per cent of coalition voters support the government's approach.