U.S. President Donald Trump signed an executive order on Tuesday that would require voters to prove they are U.S. citizens and attempts to prevent states from counting mail-in ballots received after Election Day.

President Donald Trump on Tuesday signed an executive order to make sweeping changes to the U.S. election system that critics say threaten to disenfranchise millions of eligible voters.

The order is expected to face challenges in court by civil rights groups, which argue it will disenfranchise millions of voters.