A court challenge by two Douglas County residents against Kansas Secretary of State Kris Kobach could become a class-action suit that represents many of the 36,000 people slated to have their incomplete voter registrations canceled.

Lawyers for Cody Keener and Alder Cromwell filed an amendment Tuesday to make the change.

Kobach has asked the federal court to dismiss the case because Keener and Cromwell are now registered to vote. His office registered them by obtaining proof-of-citizenship documents on their behalf, which is allowed by the registration statute.

Will Lawrence, attorney for Cromwell and Keener, said their case remains valid despite Kobach’s subsequent action to register them.

“But we also realize this case involves tens of thousands of Kansans who have ended up on the suspended voter list and are ultimately to be denied the right to vote,” Lawrence said.

Craig McCullah, Kobach’s spokesman, said Thursday the office was reviewing the class-action request and had no comment yet.

Kobach implemented an administrative rule in October to cancel incomplete voter registrations after 90 days. Most such registrations were missing proof-of-citizenship documents, such as a birth certificate or passport. The law that requires proof of citizenship for voter registration took effect in 2013.

The suit, brought by the law firm of Paul Davis, the Lawrence lawyer who ran against Gov. Sam Brownback in the 2014 election, argues that the 90-day rule violates the National Voter Registration Act and due process rights.

Kobach has said that discarding the incomplete voter registrations doesn’t remove anyone from the voter rolls, since those applicants aren’t yet registered to vote. Filling out a new registration form is a simple matter, he said.

The Public Interest Legal Foundation, formerly known as ActRight Legal Foundation, announced Wednesday that it has asked the court to accept a friend-of-the-court brief in defense of Kobach’s rule.

The group said the suit was an assault on Kobach’s effort to ensure the integrity of state elections.

“Aliens are registering to vote and voting, and Kansas is leading the effort to stop it,” said J. Christian Adams, foundation president, in a statement.

A hearing in the case is scheduled for Dec. 4 in U.S. District Court in Kansas City, Kan.