I liked this comment:
These hearings are establishing an extremely dangerous precedent, where administration figures and officials refuse to answer questions, not based on a claim of executive privilege or other legal basis but on just not wanting to answer them. If anyone else did that, I believe it would be called "contempt of Congress" and the person doing it would be subject to prosecution.
If the co-chairs of these hearings don't compel witnesses to answer questions when they have no legitimate reason to not answer them, they will have seriously eroded the balance of powers and checks on the president's power.
John McCain should shut up and try to stop embarrassing himself.