Federal grand jury subpoenas arrived at the Los Angeles County Registrar-Recorder's office last week, seeking information about how the agency detects "unlawful voting by aliens" and prevents such ballots from being counted, according to copies of the documents seen by Reuters on Oct. 29.

The subpoenas also demand records of the county's response to Justice Department letters warning officials of criminal exposure.

The escalation is striking because it arrives days before the Nov. 3 midterms and targets election administration itself, not individual suspects.

Acting Deputy Attorney-General Trent McCotter told reporters on Oct. 29 that the Justice Department has charged 156 immigrants with voting or registering unlawfully in a pre-midterm push.

Meanwhile, studies cited in reporting have repeatedly shown non-citizen voting is rare and has no effect on results, making the grand jury route an unusual use of federal criminal power against a state-run system.

California is contesting the federal campaign on multiple fronts. On Oct.

28, US District Judge David Carter rejected the Justice Department's request to temporarily block California from counting mail-in ballots of about 20,000 voters the administration alleges are likely noncitizens; the DOJ has appealed.

Before ruling, Carter told agency lawyers that threats to state and county election employees should cease immediately.

Lawyers for California have questioned the reliability of the administration's immigration data and argue the federal government lacks authority to intervene in state-run elections.

Democrats and other critics worry the push could sow doubt about the results of an election that will determine control of Congress. Los Angeles County Registrar-Recorder Dean Logan said in an Oct.

29 statement that the DOJ has taken "a confrontational, adversarial approach" at every step, while insisting officials are acting in accordance with state and federal law.

A Justice Department spokesperson declined to comment on the latest subpoenas but said both governments agree non-citizen voting is properly addressed through criminal law.

The DOJ's appeal of Judge Carter's ruling keeps the mail-ballot fight alive through Election Day, and the grand jury subpoenas suggest more legal pressure on local officials who refuse to verify citizenship status.

California is expected to keep arguing that states, not the federal government, administer elections under the Constitution. The standoff sets up a post-election test of whether federal criminal tools can be used to challenge how states run their own vote counts.