WASHINGTON ― President Donald Trump on Wednesday defended a request for voter data from his commission to investigate elections, suggesting states that did not turn over information were concealing illegal voting activity.

Trump made the comments during a surprise appearance at the first meeting of the Presidential Advisory Commission on Election Integrity. Kansas Secretary of State Kris Kobach (R), the commission’s vice chair, sent a letter to all 50 states on June 28 requesting they provide publicly available voter data ― including if possible the last four digits of voters’ Social Security numbers and voter history.

Almost every state said they could not provide that information to the commission. Some refused outright, while others said they were barred by state law from turning over information. Other states said they would provide whatever voter information was already public. The commission asked states to hold off on providing it amid a privacy lawsuit.

Trump said information from the states would be coming soon.

“I’m pleased that more than 30 states have already agreed to share the information with the commission and the other states that information will be forthcoming,” he said. “If any state does not want to share this information, one has to wonder what they are worried about. And I ask the vice president and I ask the commission, ‘What are they worried about?’”

Trump’s comments echo a tweet he sent shortly after states started refusing to provide information. The president has claimed he would have won the popular vote had it not been for illegal votes and that 3 to 5 million people voted illegally in the 2016 election. Trump didn’t explicitly repeat that claim on Wednesday, but said many had spoken to him about it during the campaign.

Michael McDonald, a political science professor at the University of Florida, suggested in an interview this month the commission intentionally asked states for information it knew it wouldn’t be able to provide. States refusing would lend credence to the idea states had something to hide, McDonald told Slate.

The commission has also been inconsistent in its claims about how the sensitive voter information would be stored. Kobach’s initial letter said all documents provided to the committee would be public, but in later court filings he said sensitive voter information would be protected. The commission also initially said the information would be stored on a Defense Department website, but now says it will be maintained on a White House server.