Liberal Senator Gary Humphries says he may cross the floor on the issue because he believes the Commonwealth should not interfere in ACT law making.
The federal government is also facing a major challenge to its plans to change laws dealing with asylum seekers coming to Australia in boats, with Coalition Senators and members of parliament threatening to revolt over the issue.
Labor's Senator Joe Ludwig says the federal government has no right to override the territorys' laws.
“If self government in the ACT is to have any meaning at all it must mean that ACT legislature can determine policy of this sort. It has no bearing on what happens outside the ACT and it has no bearing on the ACT's special role as the seat of the Commonwealth government. It will only effect the way certain relationships are treated within the Canberra community and under territory law,” Senator Ludwig said.