Considering that the Justice Department Special Council found no reason to suggest he be charged with any crime, and provide no evidence to suggest he should be impeached....I'm going with the "due process" theory.
As Sol Wachtler famously said "you can indict a ham sandwich", the trick is in successful prosecution. So far, there has been no crime uncovered in nearly 3 years of investigation....and boy have the dems tried. Sure, someone can indict him - but when it becomes clear that they have no evidence, or worse - that the evidence was fabricated (as has been done several time so far), can you say "malicious prosecution"?