COLUMBUS, Ohio (AP) — Ohio’s elections chief on Wednesday referred for possible prosecution 597 apparent noncitizens who either registered to vote or cast a ballot in a recent election — a higher number than he normally finds but still a tiny fraction of the state’s electorate.

Republican Secretary of State Frank LaRose said that of those cases, 138 were found to have cast ballots and 459 registered but did not vote. They were identified as part of a routine review and referred to Ohio Attorney General Dave Yost.

The total compares to 148 noncitizen cases referred in 2022, 117 in 2021 and 354 in 2019. More than 8 million people are registered to vote in Ohio.

Only a handful of noncitizen-related cases are ever prosecuted. However, this year’s referrals come as preventing noncitizen voting has become a centerpiece of Republicans’ 2024 campaign messaging.

Earlier this year, LaRose launched an audit of the state’s voter registration database that resulted in the removal of 154,995 registrations that he said had been confirmed to be abandoned and inactive for at least four consecutive years.

Civil rights organizations decried the effort as voter suppression. LaRose said the effort is ongoing and additional registrations could yet be cancelled before November’s presidential election.

LaRose has said his citizenship verification efforts this year are the most comprehensive the office has ever undertaken. The analysis includes cross-checks against records provided by the Ohio Bureau of Motor Vehicles, the Department of Homeland Security’s federal database of noncitizens, the Social Security Administration, federal jury pool data and other resources.