WASHINGTON — President Trump on Wednesday urged members of his new voter fraud commission to approach their task with “a very open mind,” despite having spent months making unfounded claims, without evidence, that millions of fraudulent ballots had been cast against him.

Speaking at the first meeting of the Presidential Advisory Commission on Election Integrity, Trump also questioned the motives of states that have refused to comply with the commission’s request for extensive personal voter information, suggesting they had something to hide.

“If any state does not want to share this information, one has to wonder what they’re worried about,” he said. “There’s something. There always is.”

Meanwhile, Kris Kobach, the vice chair of the commission, said in an interview with MSNBC that “we may never know” whether Trump’s 2016 rival Hillary Clinton really won the popular vote.

“We will probably never know the answer to that question, because even if you could prove that a certain number of votes were cast by ineligible voters, for example, you wouldn’t know how they voted,” said Kobach, who is also Kansas’s Secretary of State.

Trump won the Electoral College by a comfortable margin, but Clinton won the popular vote by nearly 2.9 million votes.

Even before their first meeting, the commission had drawn outrage over a request to each state for reams of personal voter information, including voter names, voting histories and party affiliations. Aides to Vice President and commission chair Mike Pence said they only asked for information that was already publicly available.

But at least 17 states, plus Washington, D.C. have rebuffed the request, citing privacy concerns and a fear that complying would legitimize the unproven idea that voter fraud is widespread. The requests have also sparked multiple lawsuits.

Critics see the commission as part of a conservative campaign to strip minority voters and poor people from the voter rolls, and to justify unfounded claims made by a president who was angry about losing the popular vote.