(1) Removal is not the appropriate sanction for this misbehavior.
(2) Trump voters will burn the party down before they let Trump lose.
(1) Demonstrate removable misbehavior.
(2) Keep the investigation transparent enough to overcome Trump follower's reflexive conspiracy-mongering.
(3) Trick Trump into self-injuring "fitness" errors.
As a result, Dems will be looking for the thing that tips him over from "Trump being Trump" to "Trump is unfit."