Was it because Comey is a weasel?
Or is it because he is a snake?
Or is because, in the words of H. A. Goodman, Comey is a fawn?
Apologies to the distinguished members of the animal kingdom for my heartless comparisons. Comey is a leaker. Comey is duplicitous. He may or may not be a perjurer but if he is honest, he is honest in a dishonest kind of way. Comey is a master of lying through omission.
Comey is a dirty cop. Comey is a corrupt cop. Possibly worse, Comey is highly incompetent. Ask the victims of IRS abuse or the survivors of the Boston Marathon about Comey's reign of error.
Impeachable offenses? The only one I can think of is that Trump did not fire Comey on Inauguration Day. I am willing to overlook the president's recovered error. Whatever else might be said about President Trump's legacy, he removed a tumor. Thank you, Mr. President.