President Donald Trump, stymied in all efforts to pass a voting restrictions bill through the Senate, announced an executive order on Tuesday attempting to crack down on mail-in voting by executive fiat. The order, among other things, imposes mandates on states for how to send out and process ballots, directs states to share information on mail-in voters with the administration, and directs the Postal Service to monitor who is voting by mail.

Many of the provisions seem to be theater, experts noted — but the order still triggered immediate alarm, and threats of legal action.

"This is a massive and unconstitutional voter suppression effort aimed at giving Trump the power to create a list of who is allowed to vote by mail," wrote voting rights attorney Marc Elias. "We know where this will go -- the targeting of Democrats for mass disenfranchisement. We will sue and we will win."

"It will be challenged because it is an unconstitutional use of authority the President doesn't have over who can vote by mail," wrote attorney and former Pennsylvania Rep. Conor Lamb. "If [Homeland Security Secretary Markwayne] Mullin valued his oath he would refuse to enforce this order or step down. But he is an election denier and will enforce it happily."

"Article 1, Section 4 gives state legislatures — not the President — the power to choose the manner of voting," wrote attorney Patrick Jaicomo.

"The president has zero power to make any changes to mail-in voting so I expect this to be another nothing-burger," wrote American Immigration Institute senior fellow Aaron Reichlin-Melnick.