The U.S. House on Thursday approved legislation requiring documentary proof of U.S. citizenship for anyone registering to vote, something voting rights group have warned could disenfranchise millions of Americans. The requirement has been a top election-related priority for President Donald Trump and House Republicans, who argue it's needed to eliminate instances of noncitizen voting, which is already rare and, as numerous state cases have shown, is typically a mistake rather than part of a coordinated attempt to subvert an election. It's already illegal under federal law for people who are not U.S. citizens to cast ballots and can lead to felony charges and deportation.