The reliably “liberal” (I have trouble using the word for illiberal people) E. J. Dionne Jr. has this figured out: The constitution is a right-wing document.
Our constitutional system of “checks and balances” only works if those in a position to operate the levers of checking and balancing do their job. It is clear that a Republican Congress and Republican appointees to the Supreme Court have no taste for such work. For the moment, President Trump is mostly unchecked and unbalanced.
Unless “constitutionalist” is a word he has trouble with.