They can condition overwhelming financial leverage AND the attempt blows up federalism.

What the president does have is the significant resources of the federal government at his disposal—which could be used as leverage to force compliance from state governments or companies. During the pandemic the federal government has control over disaster-relief funds, some medical equipment for states and billions in aid to businesses and individuals.

Mr. Trump has hinted on Twitter that some of that future federal assistance may be conditioned on fealty to federal policy—though such a step would undoubtedly provoke litigation where there is very little case law to guide courts.

Mr. Trump tweeted Tuesday, referring to Andrew Cuomo, the Democratic governor of New York: "Cuomo's been calling daily, even hourly, begging for everything, most of which should have been the state's responsibility, such as new hospitals, beds, ventilators, etc. I got it all done for him, and everyone else, and now he seems to want Independence! That won't happen!"

"Tell the Democrat Governors that "Mutiny On The Bounty" was one of my all time favorite movies. A good old fashioned mutiny every now and then is an exciting and invigorating thing to watch, especially when the mutineers need so much from the Captain," Mr. Trump added, referring to a film depicting a revolt by officers on a British warship that occurred in 1789.

If Mr. Trump were to carry through on threats to withhold federal assistance from noncompliant states, he would likely provoke a constitutional showdown that was more the hallmark of relations between Washington and the states in the 18th and 19th centuries.

"To say to states like California or New York, you're not getting another penny of federal disaster money if you leave these shelter-in-place orders in place? I mean, that's just going to provoke a federalism fight the likes of which we've never seen before," said Stephen Vladeck, a professor at the University of Texas School of Law.