Fifteen Native Americans are suing state and county officials over a lack of election services on Montana's reservations.
The Indian plaintiffs say the refusal to open offices that allow in-person absentee voting and late registration on the reservations is an unconstitutional denial of equal voting access.
The plaintiffs say they must drive long distances to their county seats to vote early or register late.
Voting access on Election Day is not an issue in the lawsuit filed Wednesday in Billings federal court.
Montanans can vote early by mail or by delivering absentee ballots in person to county offices. Late registration begins at county offices a month before Election Day.
Secretary of State Linda McCulloch said Thursday she sympathizes with the plaintiffs but she can't force counties to open satellite offices.