A new bill introduced in Congress last month aims to require proof of citizenship to register to votewhich could make an already-complicated registration process harder for millions of Americans.On January 3, Republican representative Chip Roy reintroduced the Safeguard American Voter Eligibility (SAVE) Act to Congress to ensure that our elections and our sovereignty cannot be hijacked and influenced by foreign nationals who have no business voting in this country.The SAVE Act would require voters to present physical documentary proof of citizenship to register or reregister to vote. This means passports, birth certificates, or special drivers licenses that include proof of citizenshipeither REAL ID or an Enhanced Driver License that includes an American flag to show its holders citizenship.But by introducing additional barriers to vote, this legislation could incidentally disenfranchise millions of young voters, voters of color and married women, according to an analysis published by the nonprofit Brennan Center for Justice.Why do people oppose the SAVE Act?After the 2016 election, President Trump stoked fears about noncitizen voting by falsely claiming that 3 million-to-5 million noncitizens voted in the election, but instances of this occurring are vanishingly rare, according to the Brennan Center. Noncitizen voting is already illegal in all 50 states.While the new requirements could ultimately bar noncitizen registrationwhich experts say only happens to an infinitesimal degreethey could also complicate or even block registration for millions of Americans who may not possess the required documents.Last year, the Brennan Center found that 21 million Americans dont have proof of citizenship readily available. The Enhanced Driver Licenseswhich show proof of citizenship on the cardare only available in five states. And almost half of Americans dont even own a passport.Younger voters and voters of color are less likely to have access to these required documents than others, according to the Brennan Centers analysis. The nonprofit also wrote that the SAVE Act would functionally eliminate mail-in voting registration because it requires voters to produce documentation in person to an election official.This bill may also disproportionately block married women from voting: As many as 69 million married women dont possess a birth certificate that matches their legal name, according to the Center for American Progress.The bill passed the House once in July, and with its reintroduction, it will likely see the floor again soon. But to be passed into law, the bill would need to overcome a potential Senate filibusterwhich would require unlikely support from seven Democrats.