OLATHE, Kan. — Election officials in Kansas’ most populous county didn’t offer the easiest option for registering to vote until the day before voter registration ended.

The American Civil Liberties Union told The Associated Press it’s trying to determine whether other counties besides Johnson were doing the same thing.

The Kansas City Star reports that Johnson County election officials until Monday only offered a state form that requires documentary proof of U.S. citizenship to register to vote.

After the newspaper questioned whether doing so violated the National Voter Registration Act, the office began providing to those who asked a federal form that simply requires people to attest they are citizens.

Recent court decisions have blocked Kansas from requiring proof-of-citizenship documents from people who register when getting their driver’s license or when using the federal form. Voter registration ends Tuesday in Kansas.

Kansas Secretary of State Kris Kobach has passionately supported the state law requiring such documentation, and continued to argue in court that thousands of people shouldn’t be allowed to vote until they prove they are citizens.

Johnson County election commissioner Ronnie Metsker said there was some confusion about the ongoing court cases. But he said even though the office didn’t make the federal form available until Monday, he didn’t think it impacted voter registration. He said the office had still been accepting the federal form, even though it had not been handing it out. Applicants could get the form online.

“We may have inadvertently made it awkward or some level of inconvenient,” he said. “But I don’t think we’ve stopped anyone from actually getting registered.”

Metsker said last week that he didn’t recall any direction from the Kansas Secretary of State’s office that he had to make the federal form readily available. That changed on Monday, he said, when the secretary of state’s office told the election office to change.

“We have not provided that federal form at our office for at least 12 years,” Metsker said.

Micah Kubic, the ACLU of Kansas’ executive director, told the AP he’s heard anecdotally that other counties may not have been offering the federal form to voters, though his group doesn’t yet have “hard evidence.” He said the ACLU will continue to examine whether making the form available upon request complies with federal law.

Asked whether the ACLU is considering legal action over the situation in Johnson County, Kubic said: “I wouldn’t completely rule it out, right, but I think we’re having internal discussions this morning about whether there’s anything to do.”

Sedgwick County Election Commissioner Tabitha Lehman told the AP earlier this month that federal law dictates that election officials have to provide the federal form, so her office has copies of it at the front desk and even provides copies for voter registration drives if requested.

Douglas County has always had the federal form available at its counter for registrants, said County Clerk Jamie Shew.