Control of the Senate in the 2018 midterms may hang on the fate of Heidi Heitkamp, the right-leaning Democrat from North Dakota. But her victory will be nearly impossible without the votes of the Standing Rock Sioux tribe and other Native communities across the heavily Republican state. Now, those communities are facing an insidious new threat: voter ID laws designed to strip American Indians of the right to vote.

In 2012, Heitkamp won the race for the US Senate on a razor-thin margin of 3,000 votes. Her path to victory leaned heavily on support from North Dakota’s 46,000 Native Americans, who make up 5.5% of the state population and are a core Democratic constituency across the rural west. In the 2018 midterms, Heitkamp’s re-election strategy – which could determine control of the Senate – relies on this same indigenous demographic.

Study after study has shown that Republican hoopla about voter fraud is baseless

The Republican party is well aware of this. Just five months after the 2012 election, the Republican-held North Dakota legislature passed a new voting law without any hearings or debate on the bill’s final text. The law requires North Dakotans to present at a polling station a driver’s license, state ID, tribal ID or other form of identification deemed permissible by the secretary of state in order to exercise their right to vote. In 2015, the state made the law even stricter, prohibiting the use of student, military and expired IDs, limiting the use of absentee ballots without ID and freezing the list of acceptable forms of identification.

These ID requirements present a significant barrier to Native Americans, whose communities have triple the unemployment and poverty rates of the rest of the state and who often lack transportation to travel long distances to obtain a driver’s license or state ID.

And that’s just the beginning. The law only considers identification that includes a residential address to be valid for voting purposes. This requirement disproportionately impacts Native Americans living on reservations, who often use a PO box because they live in rural homes that lack a residential address or are transient, moving from one family or friend’s house to the next.

In January 2016, a group of disenfranchised Native people who could not vote in the 2014 midterm elections filed a lawsuit alleging that the law violated section 2 of the Voting Rights Act of 1965, which prohibits voting procedures that discriminate on the basis of race. According to the suit, there is not a single site where a state ID can be obtained on a reservation. Expert testimony brought by the plaintiffs suggests almost a quarter of North Dakota’s Native American population does not have valid voter identification – twice the rate of non-Native people.

'They're billin' us for killin' us': activists fight Dakota pipeline's final stretch Read more

A federal district court judge temporarily stopped the law from taking effect. But this September, the eighth circuit court of appeals reversed that ruling. Then, on 9 October, less than a month before the election, the US supreme court declined to hear the case, upholding the lower court’s ruling.

Tribes are now scrambling to issue valid forms of identification so that their citizens can participate in our democracy. On the Turtle Mountain Indian reservation, chairman Jamie Azure signed an executive order providing tribal citizens IDs free of charge. Demand is so high that their machine has overheated and started melting the cards.

Citizens of the Mandan, Hidatsa and Arikara Nation are out knocking on doors to inform their neighbors about the strict new rules, and arranging shuttles to get families to their polling stations. North Dakota has closed polling stations in some rural counties in the western part of the state due to budgetary constraints. The Mandan, Hidatsa, and Arikara offered to subsidize the polling stations their residents rely upon, but were rebuffed.

Now some voters in their community have to drive up to an hour one-way to cast a vote in person – and that’s assuming they have access to a car or can hitch a ride on the shuttle. “It’s incredibly frustrating,” Cesar Alvarez, a Mandan, Hidatsa and Arikara citizen and an organizer for the Heitkamp campaign told me. “It’s disenfranchising people here.”

Proponents of the law, such as North Dakota secretary of state Al Jaeger, a Republican, have cited concerns about voter fraud as justification for the bill. But study after study has shown that Republican hoopla about voter fraud is baseless. Loyola Law School professor Justin Levitt has tracked US elections from 2000 to 2014 and found just 31 instances of cheating out of over 1bn votes cast. Statistically speaking, Americans cheat at the ballot box about as often as we hit the Mega Millions lotto.

Like the poll tax, literacy test and grandfather clause of the Jim Crow south, the real purpose of voter ID laws like the one now in effect in North Dakota is to plant a white thumb firmly on the political scale. Native Americans and many others across the nation – including African Americans in Texas and Georgia – are staring down the prospect of a post-civil rights era.

Trump’s words have consequences, and he can no longer deny it | Gary Younge Read more

On the Standing Rock reservation, in a community that knows better than any other what’s at stake, young and old are knocking on every single door, helping residents file absentee ballots to ensure voter turnout is high. Standing Rock youth have even decorated a Get Out the Vote bus that will drive from community to community on the reservation, transporting people to the polls.

The irony of this civil rights battle, which requires the literal first peoples of North Dakota to prove their roots are where they have been since time immemorial, is not lost on the indigenous communities leading the fight on the ground.

“We are being denied an inherent and moral right,” Judith LeBlanc, of the Caddo Nation and executive director of the Native Organizers Alliance told me over the phone between canvassing shifts at Standing Rock. “This is our territory, this is our land, and for them to say that we need to have an address in order to vote is an insult at best.”

• Julian Brave NoiseCat is an enrolled member of the Canim Lake Band Tsq’escen in British Columbia