Yet Mr. Trump’s defiance can, in and of itself, form the basis for an additional impeachment article — a fact that Nancy Pelosi, the speaker of the House, recognized on Thursday. “Ignoring subpoenas of Congress, not honoring subpoenas of Congress — that was Article III of the Nixon impeachment,” she said.

President Trump’s assertion that there is nothing left to learn from congressional hearings — which, unlike the Mueller investigation, would be televised — may be correct. But that is beside the point; it is up to Congress, not him, to decide.

He also clearly fears the dramatic spectacle that such hearings would surely provide. Once again the Nixon model applies. Who can forget the scenes of John Dean, Nixon’s former White House counsel, testifying about the “cancer on the president” and hush money payments to the Watergate burglars?