The Justice Department on Friday ordered California election officials to identify suspected noncitizens on voter rolls and set aside their mail-in ballot – warning that officials who knowingly count ballots cast by noncitizens could face criminal liability.

The stipulation marks an escalation in the Trump administration’s efforts to scrutinize voter rolls as the government continues to double down on claims of voter fraud, fueled by President Donald Trump’s baseless allegations of widespread election cheating.

Letters sent to California county election officials asked them to work with the Justice Department and Department of Homeland Security to “identify who on the accompanying list is a citizen and who is not.”“If persons knowingly tabulate ballots cast by individuals identified by federal agencies as noncitizens, they risk becoming aiders and abettors to a federal crime,” First Assistant US Attorney Bill Essayli wrote in a letter to San Bernardino County officials, seen by CNN.

The letters follow a demand earlier this month from Acting Deputy Attorney General Trent McCotter, who gave Los Angeles County and California Secretary of State Shirley Weber 48 hours to review a federal list of suspected noncitizens who had been sent mail-in ballots. McCotter threatened to seek “emergency relief” if officials did not comply.

The earlier letter, sent Oct. 13, included a password-protected thumb drive containing names of people the administration “believes are likely non-citizens” who had been sent ballots for the November election. It asked officials to temporarily set aside ballots from people whose citizenship could not be confirmed, rather than cancel their registrations.

“Maintaining accurate voter registration records is a fundamental responsibility of our office,” Los Angeles County Clerk Dean C. Logan said in a statement, after receiving the Oct. 13 letter.

“Federal and state laws are clear on how voter eligibility is established – and any action to remove a voter from eligibility must be based on verifiable information, not assertions of unconfirmed data matching.”The Justice Department last week sued California and Los Angeles County, seeking to prevent officials from counting more than 20,000 mail-in ballots associated with people the government believes are likely noncitizens. A federal judge scheduled a hearing on the case for next week, but the Justice Department on Friday asked the 9th US Circuit Court of Appeals to intervene before then.

“Every minute of processing that occurs without segregating the ballots of suspected ineligible voters causes untraceable disenfranchisement and dilution of the votes of United States citizens,” the motion noted.

A similar legal battle is unfolding in Alaska, where the Trump administration is seeking to block certification of the state’s Senate race under certain circumstances if Republican Sen. Dan Sullivan loses. The race is being closely watched as Democrats seek to regain control of the Senate. The administration has repeatedly alleged that hundreds of thousands of noncitizens are on voter rolls.

In August, Homeland Security Secretary Markwayne Mullin said his department had identified 250,000 people it believed were noncitizens and registered to vote in four states, including California, Pennsylvania, New Jersey and Nevada, by comparing voter-registration records with federal immigration data.

But the administration’s claims have faced scrutiny, and some initial findings have not held up under further review. In Nevada, for example, DHS told state officials that its initial finding of 15,900 potentially noncitizen registrants was preliminary and unvetted, and that it had confirmed only 185 through manual review.

Last month, Nevada officials told DHS their subsequent review found that all 185 were US citizens, a conclusion the federal agency disputes.

In response to Friday’s letters, Senator Alex Padilla (D-Calif.), a ranking member of the U.S. Senate Rules and Administration Committee with oversight over federal elections, called the administration “afraid and desperate.”“Trump’s DOJ has not provided any evidence for their claims of massive voter fraud. They’ve admitted that the data they point to is inaccurate and unreliable. No matter how many lawsuits they file or how many election officials they threaten, they do not have the authority to interfere,” Padilla said.

“The Trump administration is afraid and desperate. Their attempts to take over our elections will fail. Election officials: We have your back. California: Your vote is your voice. Use it and let’s hold this administration accountable.”