LOS ANGELES (AP) — A federal judge has rejected a Trump administration request to stop California from processing the ballots of up to 20,000 people, warning it would “wreak havoc” on the midterm elections.

Wednesday's ruling by U.S. District Judge David O. Carter comes as more than 3.7 million people have already voted in the state.

The decision is the latest legal setback for President Donald Trump in his efforts to expand federal control over state-run elections ahead of voting that will decide control of Congress for the rest of his term.

The Republican administration sued election officials in the Democratic state in mid-October, accusing the officials of failing to meet a 48-hour deadline to review a list of 20,000 names it alleged were likely noncitizens on the state’s voter rolls.

The administration had asked the judge to require the state to wait to count those ballots until the voters’ immigration status could be verified. The federal government also had asked the appeals court for a quick ruling — before a district judge’s scheduled Oct. 27 hearing in the case — but that effort was rejected by the higher court.

California officials warned in earlier court filings that any effort to heed the Trump administration’s requests would potentially “disenfranchise legitimate voters,” delay the certification of the election and “cause general uncertainty in the election results.”

Voting has been underway for weeks in California ahead of Nov. 3 Election Day as U.S. voters decide control of Congress.

The Justice Department made a similar request in Washington state this week for the state to sequester ballots submitted by hundreds of people it suspects are not U.S. citizens. Meanwhile, another lawsuit filed in Alaska last week seeks to delay certification of the vote if the Republican incumbent running for U.S. Senate doesn’t win. All three states have House or Senate races that will help determine the balance of power in Congress.