The bill, which would give Federal Parliament – as opposed to a federal minister – the power to override territory laws, was given support by Labour MPs in a Caucus meeting on Tuesday.
Subsequently however, a group of MPs told ABC news that the implications of the bill were not fully outlined, and that they suspected it was a deliberate “stitch up” by the Labor left and Greens MPs, who do support gay marriage.
ABC also reported that Ms Gillard said there was nothing unusual about caucus members coming to her with concerns.
“The caucus meeting on Tuesday considered an amending proposition about the ability of territories to make their own legislation.
“The Labor Party supported similar legislation in 2006, so there was a discussion at caucus and we have supported similar legislation in the past. Subsequent to the caucus meeting, a number of caucus members raised a concern with me about the breadth of that legislation.”
Ms Gillard also dismissed reports that labour members were concerned about the effect of the Greens on Government legislation.
Last November, the Green Party won a motion calling on MPs to ask their constituents about the issue.
Recent polls are showing increased support for a change in the law.
Before Christmas, Fairfax-Neilsen research found that 57 per cent of 1,400 were in favour of gay marriage, while a poll carried out for gay rights groups in October found that 62 per cent were in favour.
The Labour party will debate its policy on gay marriage at its conference this year. Ms Gillard has said she believes marriage should be between a man and a woman.