A voter drops a mail-in ballot at an official drop box inside City Hall during a primary election in San Francisco, California, on Tuesday, June 2, 2026.
David Paul Morris | Bloomberg | Getty Images
The federal government sued the state of California on Thursday in an escalating battle over how to prevent non-U.S. citizens from voting by mail in federal elections.
The lawsuit is the latest action by the Department of Justice targeting state administration of elections, which President Donald Trump has often criticized as susceptible to fraud and voting by noncitizens.
The civil complaint, which the DOJ had threatened to file, asks a judge to prevent California officials from tabulating mail-in ballots "from likely non-citizens in the upcoming federal election until the voter's citizenship status can be determined."
The Department of Justice asks that a judge order the state to set aside mail ballots from voters "identified by the Federal Government likely to be noncitizens," and to verify their citizenship status before their ballot is counted.
Non-citizens are barred from voting in federal elections.
California Gov. Gavin Newsom, in a post on X on Wednesday, said, in anticipation of the suit, "More dangerous nonsense from a President losing his grip on reality."
"Trump is now demanding that California election officials VIOLATE federal law," Newsom wrote. "Apparently, the rule of law only matters when it's convenient for MAGA's dear leader. California's elections are NOT Donald Trump's to control. We will ensure EVERY California voter can participate in a free and fair election.
The suit in U.S. District Court in Los Angeles came two days after acting U.S. Deputy Attorney General Trent McCotter, in a letter to California Secretary of State Shirley Weber, gave the state 48 hours to determine whether any U.S. citizens were on a list of people the DOJ believes are likely noncitizens who were sent ballots for the Nov. 3 election.
The DOJ previously gave officials in Los Angeles County a thumb drive containing the questioned names to officials in Los Angeles County.
McCotter told Weber the state needed to tell local election officials to segregate mail ballots until the citizenship status of their voters could be determined, and not send a ballot to anyone who had not yet received one.
"If you cannot implement this process by then, given the ongoing federal election, the United States will have no choice but to seek emergency relief," McCotter said in his letter.
Weber's office, in a statement on Thursday, said, "In July of this year, President Trump and DHS Secretary Markwayne Mullen made (still) unsubstantiated claims that California had 190,000 non-citizens on its voter rolls."
"Given the many high-profile examples of states purging US citizens from their voter rolls based on DHS/SAVE data, SOS immediately requested written information about their methodology and data sources to back up their claims," Weber's office said. "They refused and provided California with nothing."
"Now the USDOJ, under threat of 'emergency' litigation, demands that California blindly trust this administration without any evidence or legal authority to justify its request."
Weber, in a statement Thursday, said the DOJ's "relentless efforts to unlawfully gain access to states' protected voter data and purge voter rolls serve only to cause chaos and fuel public distrust in our elections."
She also said that California "has robust state law requirements that only U.S. citizens can register to vote and that any non-eligible registrants are removed from the State's voter rolls."
"My office and California election officials remain committed – as always – to ensuring a fair and smooth 2026 General Election," Weber said.
CNBC has requested comment from Weber's office about the lawsuit.