BISMARCK, N.D. (AP) — Several members of an American Indian tribe in North Dakota have filed an amended lawsuit challenging the state's voter identification laws, saying the law remains a "form of voter suppression."

Republican Gov. Doug Burgum signed legislation in April that reworked the ID laws after members of the Turtle Mountain Band of Chippewa sued the state in January 2016. The lawsuit alleged the ID requirements violated the U.S. Voting Rights Act and discriminated against Native Americans.

But the reworked law "does nothing and has everything to do with limiting people to vote," said Tom Dickson, a lawyer representing members. Dickson amended the lawsuit on Wednesday to challenge the new law.

North Dakota is the only U.S. state that doesn't require residents to register to vote, though it has required voters to provide ID since 2004. State law had allowed voters without an ID to sign an affidavit attesting to their eligibility to vote, but the Legislature removed that provision in 2013.

A federal judge essentially reinstated that provision just weeks before the November 2016 general election. The Legislature responded by passing a new law allowing voters without a proper ID to cast a ballot, though requiring such ballots to be set aside until the voter's eligibility was confirmed.

Dickson said the new law "fixes nothing." His amended lawsuit argues the provision allowing affidavits in place of an ID should be reinstated.

Under state law, acceptable forms of ID include a driver's license or identity cards issued by North Dakota's American Indian tribes. The lawsuit argues that some tribal members can't afford the required identification.

The state has argued that its requirements are reasonable. State attorneys also argue that the suing tribal members haven't shown that the burdens for them to obtain a valid ID were any more restrictive than for non-Native Americans.