Washington — The U.S. Court of Appeals for the 9th Circuit on Friday rejected the Justice Department’s request to require California to set aside disputed ballots received in the midterm election.

The panel’s 2-1 ruling represents the latest setback for the Trump administration’s efforts to expand federal influence over state-run elections. Judges Mark Bennett and Gabriel Sanchez wrote in an unsigned opinion that the Justice Department had not shown that an injunction pending appeal was justified.

“Major concerns remain that granting the United States’s requested relief might result in immense hardship to Defendants and harm the public interest by risking the disenfranchisement of eligible voters and putting the entire tabulation process in jeopardy,” they wrote.

Judge Patrick Bumatay dissented.

The administration claims California distributed ballots to roughly 20,000 people who may not be U.S. citizens. It is seeking an order requiring the state to segregate those ballots and withhold them from counting until the voters’ citizenship can be confirmed. California officials maintain that the list is deeply unreliable and likely contains many U.S. citizens.

A district court judge had already forcefully denied the request, warning that the Justice Department’s demands could disenfranchise eligible voters.

“As the district court found — and we discern no clear error — there is no feasible way to identify and segregate the ballots of specific individuals without potentially catastrophic effects on the entire system,” the appeals court wrote. It added that the relief sought by the Trump administration was “simple only in the abstract.”

The decision comes as the federal government and California continue an expansive legal fight ahead of Tuesday’s midterm Election Day. Millions of Californians have already cast ballots.

The Justice Department did not immediately respond to a request for comment.

Election officials have already processed hundreds of thousands of ballots. They say the votes are fully anonymized once processed and cannot be linked back to the voters who submitted them.

The case is part of broader federal scrutiny of local elections. The Trump administration has issued a raft of subpoenas in Alaska in connection with a spoiler-candidate controversy, and the Justice Department has provided Washington state officials with a list of alleged noncitizen voters.

RELATED: Andy Burnham’s Slave Trade Pledge Sparks King Charles Reparations Row

Also on Friday, a federal judge in Washington ordered the Trump administration to provide the disputed list of names to attorneys for the Coalition for Humane Immigrant Rights and the UCLA Voting Rights Project. The groups requested access so they could review the names and assess the list’s potential effect on eligible voters.

That order will give a nongovernmental organization its first opportunity to independently evaluate the validity of the roughly 20,000 names.

Trump administration prosecutors argue that failing to address illegal voting by noncitizens would also cause harm, contending that counting those ballots would dilute the votes of citizens.

Democratic gubernatorial candidate Xavier Becerra serves as an adviser to the UCLA Voting Rights Project.

The two organizations sued the Department of Homeland Security in early October, seeking to prevent the agency from using federal immigration records to challenge state voter rolls. Their lawsuit pointed to examples from other states in which federal data incorrectly identified thousands of citizens. The groups argue that the data-matching methods could disenfranchise or discourage eligible citizens from voting. They also say the lists could disproportionately affect naturalized citizens who have a legal right to vote.

A coalition of unions on Friday became the latest group to challenge the federal government’s efforts.

The unions, including the A.F.L.-C.I.O. and the American Federation of State, County and Municipal Employees, are asking a federal judge to temporarily bar the Justice Department from ordering local officials to stop counting ballots. They also want the court to block threats to criminally prosecute officials who refuse to comply.

Bill Essayli, the top federal prosecutor in Los Angeles, has warned that “any election official who knowingly processes the ballot of a noncitizen is opening themselves to legal jeopardy.”

The lawsuit alleges that the Justice Department’s threats against election officials could impede their ability to process votes.

It remains unclear whether the Justice Department plans to pursue criminal charges. The department does not typically subpoena people it considers criminal-investigation targets to testify before a grand jury.