Australian Marriage Equality advocates are expecting Prime Minister Julia Gillard to announce an ALP conscience vote on same-sex marriage early this week.

Australian Marriage Equality spokesperson, Rodney Croome, said if the announcement occurs it will be an admission by Ms Gillard that her opposition to marriage equality is no longer politically tenable and will embolden supporters of equality to achieve a binding policy in favour of marriage equality at the ALP's National Conference in December.

"Julia Gillard, and the shrinking rump of anti-equality Labor MPs she represents, know their blanket opposition to marriage equality is costing them public support, and now it seems they are trying to find a way to save face", Mr Croome said.

"But this is just their first defeat, by conceding a conscience vote now they will signal to marriage equality supporters that our campaign is working and that a binding pro-marriage equality policy is achievable at the Party's National Conference in December."

"By making it clear that a conscience vote is what opponents of equality want, Julia Gillard will also focus the immense support for marriage equality within the Labor Party on the single goal of achieving a binding pro-equality policy."

Mr Croome said all those Australians who have raised their voices for equality should take great pride that the Prime Minister and her fellow Labor opponents of marriage equality seem to be feeling the pressure.

"We must keep applying that pressure to ensure Labor lives up to the values of the Party as well as the clearly-articulated aspirations of its members by adopting a binding policy in favour of marriage equality," he said.

Earlier this week Opposition Leader, Tony Abbott, ruled out a conscience vote for the Coalition, but Mr Croome said he does not expect this to be final word on the issue.

"An increasing number of Coalition MPs support marriage equality and want to be able to vote for it."

"Tony Abbott wouldn't feel the need to publicly confirm his opposition to a conscience vote if he felt that his Party was on his side."

Every State Labor Leader and every State Labor Conference except NSW now supports marriage equality. The Tasmanian Labor Government became the first in Australia to formally support same-sex marriage when the issue was voted on by State Parliament last month. Both South Australian Premier Mike Rann and Opposition Leader Isobel Redmond declared their support for the issue over the weekend.