WASHINGTON / LOS ANGELES - The Trump administration asked the U.S. Supreme Court on Monday to temporarily block California from counting mail-in ballots from more than 20,000 registered voters federal officials allege are likely non-U.S. citizens, escalating a legal fight days before the midterm elections.

The Justice Department filed the emergency request seeking to prevent counting the disputed ballots until each voter's citizenship status can be verified. A federal appeals court refused the request on Friday, and U.S. District Judge David Carter in Los Angeles had previously denied the administration's request on October 28, writing that "never before in American history has the federal government, on the eve of an election, sought to coerce a state and local government to abandon their own constitutional elections procedures and bend to the will of the executive branch."

The administration argues that once California commingles the challenged ballots with lawful ones, there is no way to recover the challenged ballots. The lawsuit, filed October 15, claims California is unlawfully preventing enforcement of a 1996 U.S. law that makes it a criminal offense for noncitizens to vote in federal elections, arguing California's action violates the Constitution's Supremacy Clause.

California officials and Attorney General Rob Bonta have opposed the effort, saying the state's safeguards against noncitizen voting are robust and the lawsuit threatens to deprive 20,000 people of their right to vote based on vague accusations. The administration's process for scrutinizing voter lists to identify noncitizens is flawed and likely rife with errors, state officials said in court papers.

The list of 20,000 registered voters was amassed by the U.S. Department of Homeland Security and sent to California officials and to Los Angeles County officials. A federal judge on Sunday dismissed the administration's lawsuit concerning the U.S. Senate race in Alaska.

The administration has taken an increasingly aggressive approach toward how states run elections. The Justice Department has told election officials in all 50 states that they could face criminal prosecution if they knowingly allow noncitizens to remain on their rolls or cast ballots. It has lost a series of lawsuits seeking to obtain voter rolls, including sensitive personal information, from dozens of states.

California has 52 seats in the House of Representatives, more than any other state. Democrats need a net gain of four House seats to win a majority in the chamber.

The escalation comes as Trump's fellow Republicans are fighting to retain control of Congress in Tuesday's midterms. California is the most populous state and a Democratic stronghold. The administration has made false claims about widespread U.S. voting fraud including in the 2020 election lost to Democrat Joe Biden. Multiple studies and state audits show that ineligible voting, including by noncitizens, is rare.

The U.S. Constitution assigns the responsibility of administering elections to states, though the federal government has some oversight. The lawsuit marked a rare federal intervention in the voting process and signaled a willingness by the administration to contest the election results in court.