Support for legalizing gay marriage in Australia weakened in an opinion poll released as voters are being asked where they stand on the issue in a national postal ballot.

The government earlier this month began asking Australia's more than 16 million voters to mail in a ballot saying whether the nation should lift its prohibition on same-sex marriage. The balloting results will be announced Nov. 15.

A poll by Sydney-based market researcher Galaxy Research published in The Australian newspaper on Monday found support for gay marriage had slipped in five weeks from 63 to 57 percent. Opposition had grown from 30 to 34 percent.

The survey of 1,695 voters was taken from Thursday to Sunday. It had a 2.4 percentage point margin of error.