Federal authorities filed a lawsuit against California, citing a voter roll that contains roughly 20,000 entries belonging to individuals whose citizenship has not been confirmed, and asking a judge to bar mail-in ballots from those registrants from being tallied in the November 3 midterm contest pending a review of their eligibility.

The lawsuit, lodged on Thursday, contends that a list of names transmitted by federal authorities — on the basis that those individuals may be ineligible to vote in federal elections — never underwent the state-level review that the plaintiffs argue was legally required. Federal officials have gone to court seeking an order that would set aside ballots cast by individuals flagged through citizenship verification checks until that process is complete.

The lawsuit fits into a wider administration effort to extend federal involvement in election administration before the midterms, when both chambers of Congress are expected to see competitive races that could shift party control.

Publicly available voter registration data was matched against immigration records held by Homeland Security Investigations and partnering federal agencies, with the Justice Department characterising that comparison process as the mechanism through which individuals were identified as potentially lacking citizenship status. Officials noted that the review has not yet concluded and characterised its current output as preliminary in nature.

Federal officials forwarded a list of roughly 20,000 people they categorise as non-citizens — all of whom are said to have been sent mail-in ballots — to authorities in California, based on an announcement from the federal government. State officials were asked to go through the list of names and coordinate with federal agencies to determine whether any of the individuals held US citizenship. According to the complaint, a review that had been formally requested of California was never conducted.

Blanche, serving as Attorney General, told reporters that the allegations pointed to concerns about the integrity of elections and public trust in how votes are counted, adding that any voting fraud carried out with government involvement had no place in the country. He contended that a ruling against the state would have undermined public confidence in how elections are conducted and worked against the constitutional foundations that give the country's representative system its legitimacy.

Essayli, serving as First Assistant US Attorney, told the court that California had been given the option to purge noncitizens from voter registration lists and to set aside ballots submitted by individuals whose eligibility was in question, yet the state chose not to take either step.

The filing seeks a court order directing California to confirm the citizenship status of individuals flagged by federal authorities — whether through the state's own processes or alongside federal agencies — before those voters' mail-in ballots are counted. The filing additionally requests that vote tallies from those ballots be withheld until all verification procedures have been carried out.

Voter registration rolls and immigration records were cross-referenced by federal agencies, Mullin told reporters, as part of an effort to flag people potentially enrolled to vote without citizenship. The findings were described as early-stage, with additional review still under way.

The filing, according to Acting Deputy Attorney General Trent McCotter, puts forward the position that California permitted noncitizens to cast ballots in federal races.