WASHINGTON — The Justice Department is threatening legal action against California unless state and local officials review a list of potential noncitizens on their voter rolls.

Acting Deputy Attorney General R. Trent McCotter sent letters to California Secretary of State Shirley Weber and Los Angeles County Registrar-Recorder Dean Logan on Tuesday demanding that they review a list of possible noncitizens the federal government identified by noon on Thursday.

“Allowing noncitizens to vote cancels citizen votes,” McCotter wrote in letter, which was obtained by NBC News. “States are responsible for voter registration, and the Federal Government is responsible for maintaining immigration records to enable verification of citizenship. Working together, we can more effectively protect against voter dilution and promote election integrity.”

McCotter wrote that they provided a password-protected thumb drive with a list of individuals the federal government “believes are likely noncitizens who were sent a vote-by-mail ballot” for the 2026 election. He asked that election officials “segregate — not cancel — those individuals’ vote-by-mail ballots” until their citizenship status was determined.

“The Department of Justice sent letters to California election officials demanding immediate action to ensure that noncitizens who automatically received ballots per California law do not vote in the upcoming federal election,” a Justice Department spokesperson said in a statement. “This should not be controversial, as the criminal statute is clear: only American citizens may vote in federal elections. It is a federal crime for noncitizens to vote in U.S. elections, and the DOJ is asking California to ensure that is not occurring.”

Reuters first reported on the letters. Weber and Logan did not immediately respond to requests for comment.

All registered voters in California receive mail-in ballots, which started going out on Oct. 5.

The legal threats came amid a broader campaign by the Trump administration to zero in on what voting experts say is a relatively rare phenomenon of voting by noncitizens. Trump has long made unfounded claims that voting is marred by widespread fraud.

Election officials in a several states — including Georgia, Connecticut, Nevada, and Washington state — say they have received federal subpoenas in recent months for election records.

Some officials said they fear these actions were designed to set up possible legal challenges after the midterm elections.

“What we have seen is some groundwork laid out for post-election challenges,” said Stuart Holmes, the director of elections in Washington State. “Whether that’s the seizure of voting equipment, ballots themselves, tabulation equipment … we’re preparing for any and all eventualities in that case.”

Nevada Secretary of State Cisco Aguilar, a Democrats said officials in his state are also preparing for potential challenges to this November’s results. He added that he viewed the administration’s moves as “an effort to dissuade people from participating in the elections.”

“You have a president who’s trying to choose the voter base rather than the voters choosing the elected, and that’s not how our democracy works,” he said in an interview. “It’s the people control our elections, and when you try to take that control out, you do it through intimidation, you do it through threats, and you do it by trying to dissuade people from participating.”

Since Trump took office, his administration has brought over 100 cases involving allegations of voting by non-citizens. More than 154 million people voted in the 2024 election, according to the U.S. Census Bureau.

During the second Trump administration, The Justice Department has sought voter registration data from every state in the country. It has filed lawsuits against 30 states and Washington, D.C., for refusing.