One of the most fervid ideologues expected at the Republican convention this week — the Kansas secretary of state, Kris Kobach — has been busy shaping extremist positions in the party platform to suppress immigration, gun controls and same-sex marriage. But he also found time last week to do actual damage to Kansans with a devious, 11th-hour policy that would disqualify 17,000 of them as state voters, even though they are allowed by law to vote in federal elections.

At issue is Mr. Kobach’s zealous enforcement of a notorious law he urged Kansas Republicans to pass that requires new voters to prove their citizenship with a passport, birth certificate or naturalization papers. Federal law imposes no such burden. But Mr. Kobach continues to try to force the state requirement onto the books — brazenly persisting in the face of recent federal and state court findings that these legitimate voters are being suppressed and must be allowed their full ballot rights.

Nevertheless, Mr. Kobach, claiming the issue is unsettled while he appeals to higher courts, has ordered election officials to count the ballot choices for federal offices from the 17,000 disputed voters but ignore their state and local choices in the coming primary contests. He obviously timed this bit of contumely so that any rulings on appeals would be unlikely before this summer’s voting.