The Department of Justice is demanding California take the unprecedented step of segregating ballots associated with 20,000 people the department says are “likely” noncitizens. But an initial review by local officials suggests the list is “unreliable” and that some people on it had indicated in records they were born in the U.S. and therefore may be citizens.

The new details come from court filings submitted Tuesday by the state of California and local officials, in response to a lawsuit filed by the federal government attempting to compel the state to investigate the thousands of people before their votes are counted. The state says doing what the DOJ requests would be unfeasible this close to the election and would likely break federal and state election laws.

“At best, this litigation is a reckless political stunt,” the state wrote in Tuesday’s filing. “At worst, it threatens to disenfranchise thousands of Californians this election.”

The saga began in earnest last week when the Justice Department delivered a thumb drive to Los Angeles County that contained the list of roughly 20,000 people who investigators at the Department of Homeland Security say are “likely noncitizens” and registered to vote somewhere in California.

Initially, county officials declined to open the list, citing the security threat of inserting a thumb drive of unknown origin into a government computer. The next day, the DOJ emailed a spreadsheet with the same list.

Out of the 20,000 names on the list, only 7,035 had addresses in Los Angeles County and some were duplicates, according to a separate Tuesday court filing by Los Angeles County Registrar Dean Logan.

In declarations to the court, Los Angeles County officials wrote that they took a sample of 200 people to get a sense of how reliable the federal government’s data might be.

“The review is preliminary and quality control is continuing, but it indicates that the October List is unreliable,” wrote Monica Flores, Los Angeles County Assistant Registrar-Recorder.

Of the voters where birthplace was “meaningfully reported,” Flores wrote, “38.9% indicate that they were born in the United States, which is strong evidence of citizenship.”

It’s unclear how many people that is in total or the specifics of which records listed place of birth. NPR has reached out to the LA county clerk’s office for clarity on the numbers listed in the court filings but by Tuesday evening had not yet received a response.