"Refusing to applaud a politician is fully protected under the First Amendment's guarantee of freedom of speech," Carlton F.W. Larson, a law professor at the University of California-Davis, told the Tribune-Review. "It can't even be made a misdemeanor, much less the highest offense known to the law." 

(Larson, who is writing a book on treason and the American Revolution, last year published an op-ed piece in the Washington Post  debunking myths about treason and U.S. law in light of calls that charges be filed "against Trump officials but against all kinds of other actors as well — Hillary Clinton, Mitch McConnell, even the state of California.") 

Trump made remarks regarding Democrats and treason on Monday while visiting a factory near Cincinnati — which stands along the banks of the Ohio River, which begins its journey in Pittsburgh, which serves as capital of a region with a long history related to charges — and convictions and pardons — related to treason. 

First, though... 

What is treason? ...