The U.S. Department of Justice has threatened California with possible legal action over what it says are noncitizens believed to have received mail ballots for next month's midterm elections.

A letter sent Tuesday to Secretary of State Shirley Weber from Trent McCotter, the acting deputy U.S. attorney general, says the department has provided officials in Los Angeles County with a password-protected thumb drive that contains a list of names the federal government believes are likely noncitizens who were sent ballots to participate in the Nov. 3 election.

California mails ballots to all registered voters.