>> If he accepted $177,000 in gifts while acting as Governor, then he clearly has violated the public trust. <<
But why is that a FEDERAL crime?
Because of a Federal Statute.
Are you suggesting that our laws not be enforced? Should we overlook federal crimes because the defendant is a member of our party?
The short answer is because Congress said so, starting with the 1934 Hobbs Act and followed by subsequent legislation, if the corruption affects the spending power of the United States (federal tax dollars can only be spent on public debt, not pocketed for private purposes), if corruption affects interstate commerce, or if corruption uses the federal mails or interstate phone network.
HOWEVER, I also believe that state-level corruption violates the Guarantee Clause of the Constitution. Article 4 Section 4 of the US Constitution requires that "The United States shall guarantee to every State in this Union a Republican Form of Government."
Under that reading, if a state government becomes corrupted, then it is no longer acting with the consent of the governed and therefore fails in its responsibility to be republican. Although I'm not the first person to come up with this argument, I'm pretty sure no court has considered the Guarantee Clause argument yet. However I personally think it's stronger than the Commerce Clause stuff.