Tool
One who lacks the mental capacity to know he is being used. A fool. A cretin. Characterized by low intelligence and/or self-steem.
That tool dosen't even know she's just using him.
http://www.urbandictionary.com/define.php?term=tool
Kerry's none too bright, but he's got more than enough self-esteem for an entire nation. Over-confidence combined with incompetence - just the kind of thing we need in a senior government official.