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The Department of Homeland Security says it intends to add state driver’s license information to a swiftly expanding federal system envisioned as a one-stop shop for checking citizenship.

The plan, outlined in a public notice posted Thursday, is the latest step in an unprecedented Trump administration initiative to pool confidential data from varied sources that it claims will help identify noncitizens on voter rolls, tighten immigration enforcement and expose public benefit fraud.

According to emails obtained by ProPublica and The Texas Tribune, DHS approached Texas officials in June about a pilot program to add the state’s driver license data, but it’s not clear if the state participated.

Earlier this year, DHS added millions of Americans’ Social Security data to the Systematic Alien Verification for Entitlements, or SAVE, system, allowing officials to use the tool to conduct bulk searches of voter rolls for the first time. According to the document filed Thursday, SAVE also recently expanded to include passport and visa information.

Incorporating driver’s license information would allow election officials whose rolls don’t include voters’ Social Security numbers to conduct bulk searches by driver’s license number. Ultimately, the system would link these two crucial identifiers for the purpose of citizenship checks, said Michael Morse, a professor at the University of Pennsylvania.

“It is the key that unlocks everything,” Morse said.

State driver’s license databases often include a variety of sensitive information on drivers, including place of birth, passport number, biometrics, address, email and employment information, said Claire Jeffrey, a spokesperson for the American Association of Motor Vehicle Administrators.

Beyond the privacy concerns this creates, using driver’s license numbers in SAVE could lead to citizens being wrongly flagged as noncitizens, said Rachel Orey, director of the elections project at the Bipartisan Policy Center. Driver’s license numbers are sometimes reused and people can have licenses in multiple states. Also, if SAVE isn’t linked to live versions of state driver’s license databases, the information in the system will be outdated.

“This could have far-reaching consequences for voter access and public trust if inaccurate data were used to question eligibility or citizenship,” Orey said.

DHS says in the notice that linking to driver’s license data, which it calls the most widely used form of identification, “will allow SAVE to match against other sources to verify immigration status and U.S. citizenship, which will improve accuracy and efficiency for SAVE user agencies.”

The department did not respond to questions about the expansion.

Up until this year, SAVE was mostly used to check individual immigrants’ citizenship status when they applied for public benefits. DHS has said the aim in expanding the system was to enable election officials to check voter rolls en masse. But the agency’s data-sharing agreement with the Social Security Administration as well as Thursday’s disclosure make clear that DHS and other agencies can use SAVE for other purposes, including for immigration enforcement investigations.

Information uploaded into the system by state and local election officials and other users will be saved and may be “shared with other DHS Components that have a need to know of the information to carry out their national security, law enforcement, immigration, intelligence, or other homeland security functions,” the notice explains.

Advocacy groups have sued the federal government claiming the pooling of data in SAVE violates the Privacy Act, which is meant to prevent misuse of private data. In filings, the government has said that the Illegal Immigration Reform and Immigrant Responsibility Act of 1996 explicitly allows information sharing to verify citizenship status and that DHS would exercise caution in flagging voters as potential noncitizens.

Some privacy lawyers called DHS’ move to add driver’s license information more evidence of federal overreach. “The administration wants to get as much data as it can, however it can, whenever it can,” said Justin Levitt, a law professor at Loyola Marymount University.

The DHS notice, known as a system of records notice, allows for public comment on several aspects of SAVE’s expansion, including some already completed. Typically, such notices are filed when agencies propose changes to federal systems, and the comments are meant to inform how officials go forward. That didn’t happen in this case.

In June, email records show, DHS asked the Texas Department of Public Safety, which issues driver’s licenses and ID cards, to partner on a pilot program to add its data into SAVE.

Timothy Benz of U.S. Citizenship and Immigration Services, the branch of DHS that oversees SAVE, wrote that the planned expansion was part of the “evolution” of SAVE into a “one-stop shop for all election agency verification needs.”

“That would require collaboration with each states’ DL agency in order for us to query those DL records in order to provide that information to the querying elections agency,” Benz wrote.

Rebekah Hibbs, a supervisor in the Texas Department of Public Safety’s driver’s license division, replied that DPS is “always happy” to support the SAVE tool and agreed to talk again with USCIS.

It’s not clear what happened next. In response to questions from ProPublica and the Tribune, DPS spokesperson Sheridan Nolen said the “department does not have any ongoing projects with USCIS related to driver record information for registered voters, nor have we been asked to provide that information.”

She did not answer questions about whether DPS has given any data to USCIS. DHS did not respond to questions about whether the partnership moved forward.

Texas Secretary of State Jane Nelson announced Oct. 20 that her office had run the state’s entire voter roll through SAVE. Alicia Pierce, Nelson’s spokesperson, said the office did the check using full Social Security numbers, which it routinely obtains from the Department of Public Safety to match with registered voters.

The results showed that around 0.015% of Texas voters, or 2,724 people, are potentially noncitizens.

At least one Texas official is concerned that those initial SAVE results may not be accurate. In a court filing submitted Wednesday as part of the Privacy Act litigation, Travis County voter registration director Christopher Davis wrote that state data shows about 25% of the voters that SAVE flagged as potential noncitizens in the county had provided proof of citizenship when registering to vote.

“I am concerned that the list Travis County received from the Secretary of State is flawed and worry about the potential for voters to be improperly cancelled from the voter rolls and possibly disenfranchised as a result,” Davis’ filing says.