President Trump's Election Integrity Commission is asking all 50 states to turn over all publicly available voter registration data, including highly sensitive information about voters' political affiliation, Social Security numbers, criminal history and military status. The request was initiated by commission co-chair Kris Kobach, the secretary of state in Kansas and a fervent believer that voter fraud is widespread despite decades of evidence to the contrary. In Kansas, Kobach championed the use of Crosscheck, a multistate database of voter registration information that authorities use to check whether voters are registered in two states. Kobach has said he's interested in using a similar process to compare state voter roll data to a federal database of legal immigrants. Crosscheck's matching algorithms are highly inaccurate. A recent working paper by researchers at Stanford, the University of Pennsylvania, Harvard and Microsoft found that Crosscheck's algorithm returns about 200 false positives for every one legitimate instance of double registration it finds. "We're concerned about unlawful voter purging, which has been something that Kris Kobach has been leading the charge," said Vanita Gupta of the Leadership Conference on Civil and Human Rights and former head of the Justice Department's civil rights division. Some of Kobach's voter ID requirements have been struck down in federal court, with one federal judge ruling that they constituted "mass denial of a fundamental constitutional right."