Donald Trump signed an executive order on Tuesday aiming to restrict mail voting and create a national voter list. The move is unprecedented and has sparked concerns over its legality. The order instructs the federal government to set up a list of citizens eligible to vote in each state. It also directs the U.S. Postal Service to send mail-in ballots only to those on the list. At a White House press event, Trump said voter ID and proof of citizenship could become required. He also repeated claims that mail-in voting is prone to fraud, despite evidence to the contrary. Trump has previously criticized mail voting as a form of election fraud. Yet he has voted by mail himself, including in a recent Florida special election. The order tasks the Department of Homeland Security with collaborating with the Social Security Administration to build a national voter registry. States would then receive this information. It also instructs the postmaster general to use secure envelopes with official markings for all mail-in ballots. The attorney general is directed to withhold federal funds from states that do not comply. The order further calls for prioritizing investigations and prosecutions against officials who distribute ballots to ineligible voters. Democrats and voting rights advocates argue that the order is a form of voter suppression meant to limit participation ahead of the midterm elections. Senator Jeff Merkley of Oregon said mail-in voting protects against voter suppression tactics and accused Trump of trying to rig the upcoming elections. Experts say the executive order is likely unconstitutional. The U.S. Constitution allows states to control elections, and only Congress can pass federal election rules. Previous Trump orders attempting to impose citizenship requirements on federal voter registration were blocked by federal courts. Voting rights groups have condemned the order. The Brennan Center stated that Trump has no lawful authority to set election rules. They added that government citizenship lists are incomplete and the Postal Service is overburdened, making the plan impractical. The order’s effectiveness depends on the cooperation of the U.S. Postal Service. Legal experts say the president cannot force the USPS to deliver mail according to his directives. The Postal Service operates under a board of governors. A spokesperson said the agency would review the order. Trump has sought to bring the postal service under closer presidential control, proposing to move it under the Commerce Department, whose secretary was present at the signing. Mail-in voting is widely used in the U.S., with tens of millions of Americans casting ballots this way, including Trump himself. Nearly a third of voters used mail ballots in 2024. It is especially popular among older voters, white voters, and U.S. military members. Fraud in mail-in voting is extremely rare. A Brookings Institution report found it occurs in only 0.000043% of ballots, roughly four cases per 10 million votes. Trump has long tried to influence state elections. Earlier in 2025, he issued an order requiring proof-of-citizenship for federal voter registration and that mailed ballots arrive by election day. Much of his effort has been blocked in court. Trump has publicly stated he wants to “take over” elections in Democratic-run areas. U.S. elections are decentralized, managed by local officials in thousands of jurisdictions. The Constitution gives Congress authority over federal elections but does not grant the president control over administration. Critics, including Maya Wiley of the Leadership Conference on Civil and Human Rights, say Trump is turning the Department of Homeland Security into a tool to control elections. The administration claims the order is meant to combat alleged voter fraud, a claim that experts and data widely dispute.