In the closing days of the midterms, the Trump administration has sent multiple states lists of what it alleges are noncitizens on the voter rolls, intensifying its controversial efforts to stop those people from voting in the election.

In California, the administration claimed there were 20,000 people who could be noncitizens on the rolls, while in Washington state, the administration alleged this week that 400 possible noncitizen voters had voted 1,500 times in past elections. The Justice Department sent letters to both states demanding they set aside the ballots of those the department claimed could be noncitizens — and sued California when the state said that the request ran afoul of its laws.

The demands this month of California and Washington marked a significant escalation of the administration’s efforts to hunt voter fraud by creating lists of potential noncitizen voters, one of numerous ways the federal government has tried to prove President Donald Trump’s baseless claims of mass voter fraud.

The allegations have sparked questions about how the administration created its lists of voters who could be noncitizens — and criticism that its claims of tens of thousands of noncitizens voters have whittled down under scrutiny.

State election officials and election experts have questioned the validity of the data the Trump administration is relying on to make its sweeping allegations — in addition to the decision to bring these demands to the states as early voting in the midterm election is already underway.

At a district court hearing Tuesday in the California case, attorneys for the secretary of state, Los Angeles County and outside groups argued that the federal government’s data was outdated, flawed and was a “recipe for disenfranchisement” of US citizens.

“This is a deeply troubling process, that is trying to use social security numbers that they’ve glued to the voter file, to go fishing for anyone who has an alien number,” said Anna Baldwin, an attorney arguing on behalf of the League of United Latin American Citizens and NAACP.

Bill Essayli, first assistant US attorney for the Central District of California, argued that the federal government had “developed credible evidence” of noncitizens on the rolls that California refused to address.

Essayli argued that the federal government was trying to “protect votes of lawful citizens.”While much of the case focused on whether the federal government could preempt state election law when the Constitution primarily gives the power to administer elections to the states, the circumstances surrounding how the government came up with the lists of voters were also a frequent point of contention.

Essayli offered to have the DHS officials who submitted sworn statements testify at Tuesday’s hearing to help explain the process that was used to determine the voters on the list were not citizens.

Instead, US District Judge David Carter, a Clinton appointee, said he’s appointing a special master to dig into the data provided by both the federal government and Los Angeles County, ahead of the state’s December 3 deadline to cure ballots.

Ahead of Tuesday’s hearing, a three-judge panel of the 9th Circuit US Court of Appeals rejected the Justice Department’s California lawsuit on Monday in a 2-1 decision on procedural grounds. But the two judges who sided with the state, Trump appointee Mark Bennett and Biden appointee Gabriel Sanchez, both wrote in concurring opinions they also would have ruled against DOJ.

In his opinion, Sanchez wrote that California and LA County “have expressed serious doubts about the accuracy and reliability of the United States’ data and methodology used to generate this list and contend that this extraordinary request threatens to disenfranchise thousands of California voters.”He asked several pointed questions during Sunday’s emergency hearing about the data and list the Justice Department was using to make its claims and how the Trump administration arrived at its conclusions.

“Your claims very much depend on the reliability of that list,” Sanchez said to DOJ attorney Matthew Donnelly.

The Trump administration has claimed even larger numbers of noncitizens on state voter rolls. After Trump’s July primetime speech on election fraud, Department of Homeland Security Secretary Markwayne Mullin claimed there were more than 190,000 voters registered in California who “may be” noncitizens.

California was one of several Democratic-run states that Mullin singled out after Trump’s speech.

“We’ve identified 250,000 noncitizens registered to vote in just four states,” Mullin told reporters, citing findings in California, New Jersey, Pennsylvania and Nevada.

While Mullin stated the figures as facts, those numbers have shrunk considerably under scrutiny in the months since.

In Nevada, for instance, DHS alleged it had identified 15,903 noncitizens on the state’s voter rolls. But in a follow-up meeting, DHS officials told the state they had “confirmed” just 185 Nevada registrants as noncitizens through manual review.

Nevada election officials pushed back. “As for the 185 individuals, our records indicate that they were citizens. You have provided nothing of substance to suggest otherwise,” a Nevada official wrote to DHS last month.

Donnelly, the DOJ attorney, disputed this at Sunday’s hearing, however, saying that Nevada’s leaders were basing this solely on voters attesting they were citizens when they registered.

“That, candidly, we do not think constitutes proof that our list was invalid,” he said.

Asked about the downward shift in California from 190,000 voters to the 20,000 now being alleged, Donnelly said during Sunday’s hearing that the lower number was the result of further checks by DHS.

After a review of more than 100 million voter records across both Democratic- and Republican led states, DHS is still claiming it has found 300,000 “potential” noncitizens. As of mid-September, the agency had opened 1,620 investigations based on the review, and so far, the effort has led to around 160 arrests.

During Tuesday’s court hearing, Carter told Essayli that the government already had a way to handle noncitizens who voted. “You’ve got a remedy for goodness sakes, go out and indict,” the judge said incredulously.

A DHS spokesperson said in a statement that “190,000 remains the number of potential noncitizens registered to vote in California that DHS asked Secretary (of State Shirley) Weber to review.”

“The 20,000 referenced by DOJ is a subset of registrants that have gone through the manual verification process so far,” the spokesperson said, adding that the DHS process was a “commonsense step to secure our elections.”DHS has been vague in correspondence to states about how it came up with its lists of voters it believes are noncitizens, but more details have emerged in the California lawsuit.

USCIS and Homeland Security investigations officials have said in court filings they obtained California’s public voter list in August 2025. While the voter list was obtained from the secretary of state’s office, DOJ redacted who specifically obtained it from the state.

The Trump administration “was supplied a list that was purchased” from California, Donelly said during Sunday’s hearing.

Earlier this year, DHS began analyzing the file, and it used a third-party system to further analyze the data and compare it to DHS immigration databases to identify potential noncitizens. Then, DHS officials say they checked the findings against federal databases and conducted manual checks of voter files.

“These processes resulted here in a culled list of people who are likely to be noncitizens and who registered to vote in the upcoming 2026 federal election,” wrote Nicolas Bartell, associated director of Fraud Detection and National Security Directorate at USCIS.

Wren Orey, managing director of the Bipartisan Policy Center’s Elections Project, said the third-party information appeared to be used to “backfill personally identifiable information based on the information on the publicly available voter list.”“That seems to me like a big risk that they were getting high rates of false positive matches,” Orey said.

While Donnlly said he did not know the third parties used during Sunday’s 9th Circuit hearing, Bartell wrote in his declaration this week that USCIS “enhances” the voter roll data through Lexis Nexis’ Accurint, a commercial data company.

In a whistleblower report filed with Democratic Sen. Alex Padilla of California, the whistleblower alleged that certain information not included in the source data was brought in through a process referred to as “supplemental magic.”DOJ is relying on a voter list in California that’s publicly available, because the state rejected the Justice Department’s attempt to obtain its unredacted voter file, which would contain sensitive information like Social Security numbers. DOJ has sought unredacted voter lists from nearly every state and has sued roughly 30 states that refused to turn them over but has lost every court decision on the matter so far.

Christina McCall, an attorney for the state, argued that the government’s explanation doesn’t sufficiently spell out the way that the administration compiled its data — or how it even obtained the state’s voter rolls.

“They’re not reliable, they’re vague, and they lack personal knowledge,” she said of the state’s lists of alleged noncitizen voters.

Bartell stated in his declaration that USCIS compares the data it compiles against databases from the State Department and Social Security Administration to weed out US citizens on its lists who have a passport, confirming they’re citizens, or have died.

The immigration agency then assigns a “confidence level” for each possible noncitizen match, followed by a manual review. Those cases are then referred to HSI for further investigation.

In separate litigation, which led to a federal court last week ordering DHS to stop certain investigative actions in its hunt for noncitizen voters, DOJ attorney Kelsey Helland argued that the groups suing did not have evidence that US citizens were impacted by the steps DHS took going from large list of suspected noncitizen voters to a smaller list of individuals who are investigated.

“That’s the initial step, and it goes through various sources of cross-checking databases, and there’s safeguards where USCIS officers are instructed not to keep going if it appears that a person is a citizen,” Helland said during a District Court hearing last week.

In that litigation, a redacted HSI official touched on the potential inaccuracies in the agency’s data. “When potential inaccuracies were identified in the USCIS lists, DHS sought further resources to prevent inaccuracies and developed a new model for generating leads for HSI’s unlawful voting investigations,” the official wrote.

Over the past year, DHS has also sought to identify noncitizens on voter rolls through its Systematic Alien Verification for Entitlements database — known as “SAVE” — particularly in states that voluntarily turned over their unredacted voter files. The Supreme Court allowed the federal government to continue using SAVE for its investigations last month, but DHS said that the database was not used to compile the list it sent California.

Election experts say that it’s still not clear how reliable the DHS matches may be, especially given that the Trump administration is using a publicly available voter file, not the state’s list that contains personally identifying information like Social Security numbers.

“We still don’t have all the information about what kinds of databases are used. And then more to the point, what level of matching is sufficient,” said Derek Muller, an election law professor at Notre Dame Law School.

California has argued in court filings that the DHS voter file used to compile the list of 20,000 voters it believes could be noncitizens is based on data more than a year old and could be subject to false positives.

“The Executive’s own declarations describe a bulk data match that began with a voter roster more than a year old, obtained from an unidentified source, supplemented through an unnamed commercial platform, and compared against federal databases,” Los Angeles County Registrar Dean Logan wrote in a factual declaration for the case.

“Other states’ experience confirms why such matches require investigation and individualized proof,” Logan added.

Logan’s office took a sample of 200 voters from the 7,035 names with LA County addresses. His office found that of the 200 individuals, 42.9% had canceled voter registration records and 4.6% were considered inactive, meaning they were not mailed ballots this year, Aman Bhullar, an assistant registrar/recorder who works on IT and technology, wrote in a declaration.

Bhullar said that more than 71% of the sample had never voted, and 38.9% of those who had a birthplace reported indicated they were born in the US.

In Washington state, which received the letter from the Justice Department Tuesday, the secretary of state’s office noted that one of the 400 records was from 1994. “The system the DOJ uses frequently flags legitimate U.S. citizens as noncitizens, jeopardizing their legal right to vote,” the secretary of state’s office said in a statement.