 The House has approved legislation today requiring voters to show proof of citizenship to register to vote. It's a Republican effort aimed at preventing non-citizens from voting, which is already federally prohibited. More from NPR's Ashley Lopez. Opponents have called the bill a solution in search of a problem because non-citizen voting is already illegal at the federal level. And no states currently allow it at a state level. Ultimately, critics say this effort is aimed at preventing something that is extremely rare in American elections.