But two efforts, one each from the White House and congressional Republicans, have made the prospect of a national proof of citizenship requirement a real possibility. In Congress, the so-called SAVE Act would similarly mandate proof of citizenship documents. And if voters needed to provide documentary proof themselves, millions would be at risk of disenfranchisement. Both the White House efforts and the SAVE Act are also strangely vague when it comes to what documentation is required. Both mention passports as an acceptable proof of citizenship, but half of American citizens don’t have a valid passport.