Right Hand Mouth

An obsequious (suck up) loud mouthed assistant, who serves no observable purpose other than to vociferously agree with and support whatever idea the boss has come up with.

"That Bob is Mister Big's right hand mouth."

Keep in mind this is all in good humor, and I have provided "equal time" for both parties:

Democrats: Condy is the president's right hand mouth.

Republicans: Bill is Hillary's right hand mouth.

TV Version: Dwight ("The Office") is Michael's right hand mouth.