The six members of the Fort Peck Reservation want satellite voting offices in their communities for late registration and to vote before Election Day without making long drives to a county courthouse.

The legal challenge, filed in state court, comes five weeks before the presidential election in a state with a a pivotal U.S. Senate race where the Republican candidate has made derogatory comments about Native Americans.

Native Americans were granted U.S. citizenship a century ago. Advocates say the right still doesn't always bring equal access to the ballot.

Many tribal members in rural western states live in far-flung communities with limited resources and transportation. That can make it hard to reach election offices, which in some cases are located off-reservation.

The plaintiffs in the Montana lawsuit reside in two small communities near the Canada border on the Fort Peck Reservation, home to the Assiniboine and Sioux tribes. Plaintiffs' attorney Cher Old Elk grew up in one of those communities, Frazer, Montana, where more than a third of people live below the poverty line and the per capita income is about $12,000, according to census data.

It's a 60-mile round trip from Frazer to the election office at the courthouse in Glasgow. Old Elk says that can force prospective voters into difficult choices.

"It's not just the gas money; it's actually having a vehicle that runs," she said. "Is it food on my table, or is it the gas money to find a vehicle, to find a ride, to go to Glasgow to vote?"

The lawsuit asks a state judge for an order forcing Valley and Roosevelt counties and Republican Secretary of State Christi Jacobsen to create satellite election offices in Frazer and Poplar, Montana. The offices would be open during the same hours and on the same days as the county courthouses.

The plaintiffs requested satellite election offices from the counties earlier this year, the lawsuit says. Roosevelt County officials allegedly refused, while Valley County officials said budget constraints limited them to opening a satellite voting center for just one day.

Valley County Attorney Dylan Jensen said there were only two full-time employees in the Clerk and Recorder's Office that oversees elections, so staffing a satellite office would be problematic.

"To do that for an extended period of time and still keep regular business going, it would be difficult," he said.

A spokesperson said Jacobsen's office had encouraged tribes and counties to work together to establish satellite offices as needed by Jan. 31, under a 2015 state elections directive.

"These types of conversations, as indicated by the directive, need to have occurred months ago," said Jacobsen's communications director Richie Melby.

Melby added that Jacobsen's office served all Montana voters and said the dispute had been stirred by "political activists."

Roosevelt County Clerk and Recorder Tracy Miranda did not immediately respond to a request for comment.

Prior efforts to secure Native American voting rights helped drive changes in recent years that expanded electoral access for tribal members in South Dakota and Nevada.

A 2012 federal lawsuit in Montana sought to establish satellite election offices on the Crow, Northern Cheyenne and Fort Belknap reservations. It was rejected by a judge, but the ruling was later set aside by an appeals court. In 2014, tribal members in the case reached a settlement with officials in several counties.

Monday's lawsuit said inequities continue on the Fort Peck Reservation, and that tribal members have never fully achieved equal voting since Montana was first organized as a territory in 1864 and Native Americans were excluded from its elections. Native voters in subsequent years continued to face barriers to registering and were sometimes stricken from voter rolls.

"Equal means equal," said Bret Healy, an expert witness for the plaintiffs who was also involved in the 2012 Montana case. "It is substantively, mathematically and logically not equal if there's not a satellite office on the Indian Reservation."