DES MOINES, Iowa (AP) — Some Iowa voters were improperly removed from registration rolls by county election officials after challenges to their registration status were filed too close to the election, Iowa’s top election official confirmed Wednesday.

County auditors may have processed removals stemming from challenges that were filed within 90 days of the election — a designated “quiet period” during which only limited changes can be made to voter rolls, said Iowa Secretary of State Paul Pate.

The secretary of state said his office directed county auditors to contact their attorneys and get the voters put back on the rolls. He said “most, if not all those counties” have done that.

“Clearly we’re going to be following back up on that to make sure, but it has been addressed, and we hope that it’s been corrected,” he said.

The American Civil Liberties Union and its Iowa affiliate highlighted the issue Tuesday, saying that individuals contacted their organization after being notified by their county auditor that their registration status was being investigated because of a challenge.

Pate did not say how many voters were actually removed. The ACLU identified three counties that saw mass challenges. The Associated Press left messages with those three county auditors seeking the information.

The National Voter Registration Act requires a 90-day quiet period ahead of elections for the maintenance of voter rolls so that legitimate voters are not removed from the rolls by bureaucratic errors or last-minute mistakes that cannot be quickly corrected.

The act also protects against removal of voters because of a change of address unless the voter themselves confirms they moved or unless the voter fails to respond to a written notice and does not vote in two general federal elections.

Iowa law separately has a 70-day freeze period, requiring that most challenges to a voter’s registration status be filed before Aug. 27.

“It is deeply concerning to us that auditors may have improperly removed some Iowa voters,” said Rita Bettis Austen, legal director of the ACLU of Iowa. “No action should have been taken” because of the mandated quiet period, she said.

Bettis Austen suggested county auditors in at least three of Iowa’s 99 counties received mass voter challenges, which are often using outdated or incomplete information based on comparisons of voter rolls to other databases. In a statement, she said they “appear to be the type of malicious, mass voter challenges by individuals and groups who want to disrupt the election,” but did not specify further on how they originated.

Election officials across the country are facing heightened scrutiny around voter fraud in 2024, the first presidential election after former President Donald Trump’s false claims of widespread fraud in 2020.

Now, too, accusations that people who are not U.S. citizens are registering to vote and voting have become a major throughline of conservative campaigns across the country. Voting by people who are not U.S. citizens is illegal in federal elections but there is no evidence that it is occurring in significant numbers, though some states, including Iowa, have identified dozens of such cases.

On Wednesday, the Supreme Court’s conservative majority allowed Virginia to resume its purge of voter registrations that the state says is aimed at stopping people who are not U.S. citizens from voting.

The Justice Department and a coalition of private groups sued Virginia earlier this month, arguing that state election officials, acting on an executive order issued in August by Republican Gov. Glenn Youngkin, were striking names from voter rolls in violation of the federal election law’s quiet period.

Last week, Pate sent Iowa’s county auditors a list of more than 2,000 names of people who told the state Department of Transportation that they were not citizens but later registered to vote. Pate on Wednesday acknowledged that those individuals may now be naturalized citizens and stressed they have not been removed from the rolls. Instead, poll workers will challenge their ballots and voters will have seven days to prove their citizenship status.