Officials say a computer error in Illinois' new automatic voter registration system may have led to 545 non-U.S. citizens being registered to vote, 15 of whom cast ballots. The Illinois secretary of state's office has acknowledged the mistake, saying it was an isolated incident. Officials are working to confirm how many people were mistakenly registered and canceling improper registrations. A group of Republican lawmakers has called for an immediate hearing into the issue, calling it a “serious breach'' of voter protections. Illinois made automatic voter registration law in 2017, but it wasn't fully in swing until last year.