The idea is apparently that failing to participate even in a single midterm election, which more than half of registered voters typically fail to do, constitutes evidence that a voter may have moved. The United States Court of Appeals for the Sixth Circuit disagreed and halted the practice, which prevented the state from throwing away 7,500 ballots in the 2016 election. The Supreme Court will review the case in the fall.

For more than 20 years, the Department of Justice has consistently argued that such purges based on nonvoting are illegal, and has threatened legal action against states that do not follow the law.

But it wouldn’t be shocking if the commission comes out in favor of unreliable purges like Ohio’s. And the Trump administration might make the Justice Department an accomplice in such efforts by reorienting the priorities of the Civil Rights Division away from protecting voters, in favor of actively supporting states’ efforts to cull the registration lists. That’s the opposite of elections integrity, which requires making sure that eligible voters are not kicked off the rolls.

We can also expect new proposals to limit access to the ballot. During the presidential transition, Mr. Kobach was photographed meeting with Mr. Trump and carrying a document that appeared to propose amending the federal motor-voter law, a document that he has refused to make public. That’s alarming: The motor-voter law has been a critical bulwark protecting voters’ rights against Mr. Kobach’s schemes, including his “show me your papers” law that requires voter registration applicants in Kansas to provide a citizenship document like a passport or a birth certificate when registering to vote.

That requirement makes voter registration drives all but impossible, as very few people carry such documents around with them, and fewer are likely to share them with strangers. It seems probable that the commission is a Trojan horse for the Trump administration to propose changes to the federal law that has stymied Mr. Kobach’s voter suppression agenda, and thus allow him to replicate it nationwide.

Fortunately, elections officials in more than 20 states have announced that they will either not comply at all or refuse some aspects of Mr. Trump’s demand for our data. Mr. Trump has implied that these states are up to no good, asking in a tweet, “What are they trying to hide?” That’s pretty rich, given that Mr. Trump has so far failed to make the names of the commission’s staff public and that the commission’s “organizational call” was convened without public notice and was not open to the public.

The Mississippi Republican secretary of state, Delbert Hosemann, said on Friday that the commission can “go jump in the Gulf of Mexico.” Voters in all other states should demand a similar response from their elections officials, who should refuse to participate in this charade. Our elected officials should be doing everything they can to preserve and advance the right to vote, not endanger it.