Facing skeptical questions from state Senate Democrats on Thursday, Texas Secretary of State David Whitley defended his handling of an ongoing investigation that questioned the citizenship of 95,000 registered voters, many of whom have since been found to be U.S. citizens.

Democrats repeatedly pressed Whitley to acknowledge that the list of suspect voters was riddled with errors, including thousands of people who are naturalized citizens or had registered to vote after showing proof of citizenship.

But Whitley, appearing at a confirmation hearing before the Senate Nominations Committee, said the citizenship data was the best available from the Department of Public Safety and insisted that his office took pains to double check the information.

State Sen. Carol Alvarado, D-Houston, said too many easily identified U.S. citizens were included in the list of suspect voters.

“There seems to have been a lack of due diligence,” Alvarado said. “The conclusion that I draw is either you or someone in your administration didn’t check your work product, or (you) intentionally allowed information that was inaccurate to go out.”

Whitley characterized the citizenship investigation as a process, with his office comparing voter rolls with DPS data on noncitizens, then providing matching names to counties for further investigation as required by state law. County elections officials have more pertinent information at hand than is available to his office, he said.

“My office has no investigative authority. That’s why it is important to get the data to the counties to do that investigation,” Whitley said.

But Sen. Kirk Watson, D-Austin, drilled down on that detail, asking why Whitley sent the names of all 95,000 suspect voters to Attorney General Ken Paxton because, as Whitley stated in a Jan. 25 news release, his office lacked the “authority to investigate or prosecute alleged illegal activity.”

The only reason to make that immediate referral to law enforcement, Watson suggested, was to create the appearance of widespread illegal activity.

“That could have waited until you had the verification of numbers” from the counties, Watson said.

Whitley said his only goal was to ensure the most accurate voting rolls possible, something he repeated frequently during the hearing.

Questions from committee Republicans tended to focus on the legal requirements behind the citizenship investigation without criticizing Whitley’s handling of the matter, although Sen. Lois Kolkhorst, R-Brenham, pointed to “some regrettable statements” in a Whitley press release that had trumpeted the discovery of 95,000 potential noncitizens who had registered to vote, including 58,000 who had cast at least one ballot.

The Nominations Committee, with four Republicans and three Democrats, is expected to vote on whether to send his name to the full Senate on Feb. 14.

Whitley has served as secretary of state since Gov. Greg Abbott appointed him to the job Dec. 17, but he will need the approval of two-thirds of senators to continue serving.

Whitley — a lawyer since 2012, the year he graduated from the University of Texas School of Law — has served as Abbott’s deputy chief of staff and appointments director. He began working for Abbott in 2004 in the attorney general’s office, where he rose to assistant deputy attorney general.

Whitley’s Jan. 25 announcement about possible illegal voter registration was greeted with alarm primarily by Republicans, including Paxton, who said his office stood ready to investigate the matter, and President Donald Trump, whose tweet jumped to the mistaken conclusion that Texas had discovered 95,000 cases of voter fraud.

But Democrats and civil rights groups questioned the accuracy of Whitley’s investigation, noting that the evidence came from people who told the DPS that they were not citizens, but were in the country legally, when they applied for a Texas driver’s license or identification card. The DPS data would not identify those who later became naturalized U.S. citizens, they said.

After Whitley’s office sent the names to county officials to verify citizenship, significant errors were quickly discovered, including duplicated names as well as people who had registered to vote at a DPS office after presenting proof of citizenship.

County elections officials also began finding significant numbers of people on the list who had become naturalized citizens.

In response, civil rights groups and voters filed three federal lawsuits arguing that the investigation should be stopped because it was intended to suppress voting by minorities, primarily Latinos, and could require naturalized citizens to prove citizenship, a hurdle other voters do not face.