The Justice Department sent letters this month to county registrars across California seeking information to verify the citizenship of flagged voters and directing officials not to count their ballots in the meantime. Santa Clara County Executive James Williams and County Counsel Tony LoPresti said in letters to the U.S. Attorney’s Office that the county’s registrar could not comply under state and federal law.

The federal government identified 902 Santa Clara County voters as “likely aliens.” Williams questioned how the list was assembled, saying it included duplicate entries and names that did not appear to belong to county voters. He also said the Justice Department had not provided a warrant for the Social Security numbers and driver’s license information it sought.

Williams called the federal letter “deeply disturbing and entirely inappropriate,” particularly because it threatened election officials with criminal and other legal sanctions. He said the Justice Department did not have authority to require local election workers to conduct the requested review.

County officials also cited the National Voter Registration Act, which bars systematic removals of ineligible voters from registration rolls within 90 days of an election. California voters attest under penalty of perjury that they are U.S. citizens when registering.

The dispute is part of a wider federal effort targeting voter rolls in California. Earlier this month, the Justice Department sued the state and Los Angeles County over records for voters it considers likely to be noncitizens. At a Sunday hearing, federal attorneys asked the U.S. Court of Appeals for the 9th Circuit to halt ballot counting for 20,000 voters on the list. Nearly 3 million Californians had already voted in the Nov. 3 election, according to the report.

The appeals court declined to intervene Monday, ruling that the federal government had not given a district court enough time to consider its request for an emergency order. The judges also noted that the administration had raised concerns about California’s voter rolls for months before filing suit. A federal district court judge in Los Angeles is scheduled to hear the government’s request Tuesday.

Federal officials say the effort is intended to prevent noncitizens from voting in federal elections. Election experts have questioned the legality of the demands, and cases of voter fraud are rare. Last week, federal agents charged 28 noncitizen California residents with illegally voting or registering to vote; none had been convicted as of Monday. The accused represent 0.0001% of the state’s registered voters, according to the report.

Rick Hasen, director of the Safeguarding Democracy Project at UCLA School of Law, said the probe may also serve to amplify claims of widespread noncitizen voting. Williams’s objections reflect a broader conflict over whether federal authorities can compel local election officials to provide voter data or delay the counting of ballots close to an election.