A federal appeals court will hear arguments August 25 in a lawsuit by Kansas and Arizona attempting to force the federal government to help them enforce proof-of-citizenship requirements for new voters.

The 10th U.S. Circuit Court of Appeals in Denver announced its plans Monday.

The hearing will take place after Kansas’ Aug. 5 primary election but a day before Arizona’s primary.

The lawsuit was filed last year by Secretaries of State Kris Kobach of Kansas and Ken Bennett of Arizona. They want to force the federal government to add instructions to its national voter registration form telling new voters in those states that they must provide proof of U.S. citizenship when registering.

A federal judge in Wichita ordered the change, but the federal government appealed his decision.