A top election official in the U.S. state of Arizona said he would file a lawsuit Tuesday that could bar nearly 100,000 citizens from voting in state and local elections this fall because they allegedly failed to provide citizenship documents required under state law.

The proposed lawsuit by Maricopa County Clerk Stephen Richer is based on a specific part of Arizona’s election law that requires residents to provide documents proving their citizenship in order to vote in state and local elections. Such documents are not required for Arizona residents to register to vote or to cast their ballot in federal elections. Like many other states, Arizona requires an “oath of U.S. citizenship” to vote in federal elections.

Under Arizona state law, residents who cannot provide documentary proof of their citizenship or whose U.S. citizenship cannot be verified through their driver’s license registration records or other entries in the statewide voter registration database may only vote in federal elections.

In a lengthy post on X, Richer, who helps oversee elections in the swing state’s largest county, said his office discovered a “glitch” in the way state agencies and systems verify citizenship using driver’s license registration records, which resulted in 97,000 people who swore they were U.S. citizens failing to provide documented proof of their citizenship.

“All of these individuals have affirmed, under penalty of perjury, that they are U.S. citizens. And in all likelihood, they almost all are U.S. citizens,” wrote Richer, an elected Republican. “But they have provided NO documented proof of their citizenship.”

If those 97,000 people cannot provide appropriate documentation, they will not be able to vote in state and local elections this fall, Richer said.

The lawsuit, filed in the state Supreme Court, comes as Republicans nationwide are trying to crack down on noncitizen voting, which former President Donald Trump and his allies have portrayed as a widespread problem, even though it is illegal and rare.

However, Richer is an outspoken defender of the swing state’s electoral process and has vigorously pushed back against the unfounded claims of voter fraud that proliferated after the 2020 and 2022 elections. He lost his Republican primary in July to Justin Heap, a Maricopa County elections critic who dodged questions about possible voter fraud in the 2020 election.

Regardless of the outcome of the lawsuit, the affected group of voters will still be able to participate in Arizona’s important presidential and Senate elections this year. However, it remains possible that they will be barred from voting in contested elections later in the election cycle, including state legislature elections and a proposed constitutional amendment to enshrine abortion access.

Since 1996, Arizona residents have been required to prove their citizenship to obtain a driver’s license. Since 2004, “the vast majority of voter registration applicants have satisfied their proof of citizenship requirements for voter registration by filing that proof with the Division of Motor Vehicles,” Richer explained.

“To confirm this, voter registration simply conducts a check with the MVD to ensure that the voter obtained his or her license after 1996,” he wrote.

But Richer’s office discovered an error that caused a certain group of residents – who obtained a driver’s license before 1996 and later a replacement – to be automatically considered by the statewide voter registration system and the Department of Motor Vehicles as having “documented proof of their citizenship on file with the Department of Motor Vehicles,” when they did not.

Richer said he has worked with state agencies, including the offices of Governor Katie Hobbs and Secretary of State Adrian Fontes (both Democrats), “to address this issue going forward.”

“We inherited this problem, we are working on it and we will solve it,” Fontes said in a statement. “It’s that simple.”

A press release from Fontes’ office states: “Since 2004, these requirements have been significantly tightened. Recently, officials discovered that some longtime Arizona residents who were registered under less stringent rules had not been required to comply with the new standards due to a coding oversight. To address this issue, the state has taken legal action to ensure that these predominantly Republican voters can fully participate in the 2024 election.”

Fontes’ office said he will ask the state Supreme Court to allow all affected voters to receive completed ballots and give voters the opportunity to submit the required documents before Election Day.

In a statement, Hobbs said her “team has identified and corrected an administrative error that originated in 2004 and affects long-time residents who obtained their driver’s licenses before 1996.”

Hobbs said her office will “conduct an independent audit to ensure that the MVD systems are functioning as required to support voter registration.”