AUGUSTA (AP) — The biggest contributor to the group trying to overturn Maine’s gay marriage law is suing the state over its campaign reporting requirements.

The state ethics commission voted Oct. 1 to examine contributions by the National Organization for Marriage after it was accused of not reporting the names of many donors. The group responded with a constitutional challenge filed Wednesday in federal court in Bangor.

NOM has been the leading contributor to Stand for Marriage, which is seeking to overturn Maine’s gay marriage law. Joining in the lawsuit is American Principles in Action.

A hearing is scheduled for Monday, but there’s no practical impact to this election cycle because the ethics commission investigation won’t be completed before the Nov. 3 election.