Go ahead and start impeachment. I push for treason:
Cramer v. United States, 325 U.S. 1 (1945), the Supreme Court ruled that "[e]very act, movement, deed, and word of the defendant charged to constitute treason must be supported by the testimony of two witnesses." In Haupt v. United States, 330 U.S. 631 (1947), however, the Supreme Court found that two witnesses are not required to prove intent, nor are two witnesses required to prove that an overt act is treasonable. The two witnesses, according to the decision, are required to prove only that the overt act occurred (eyewitnesses and federal agents investigating the crime, for example).