I think this nails it: Comey is blackmailable. Hillary has dirt on him, and so does someone else. That's why he's being pulled in so many different directions. He has at least three masters (Hillary, someone else opposed to Hillary, and the actual elected president).
But note the careful wording of this denial. Comey admits to some sort of investigation of Trump or his associate's connection to Russia. But then he denies that the FBI or DOJ had conducted a phone tap of Trump's phones specifically, and specifically that Barack Obama ordered it personally.
What if Trump's associates phones were the ones tapped, as news organizations breathlessly reported not long ago? What if Obama did not personally order it through the FBI or DOJ -- what if it was performed through the CIA, NSA, or British intelligence? (Comey did also deny that it was done through British intelligence, but how would he know?)
I can't imagine a good outcome here. Does the Deep State think that if they somehow unseat a legitimately elected president that the people will meekly roll over and accept it?
UPDATE: House Intelligence Chairman confirms "incidental" surveillance of Trump. As the puppy-blender is fond of saying, Trump should be taken seriously but not literally, while the media insists on taking him literally but not seriously. In this case, it appears that Trump's claim was accurate, and the FBI is refusing to cooperate with the House investigation.