Who is the principal agent in public policy making?

In general their is no one top agent in the policy process. That said, if we look at TARP Paulson and ?Bernake? were the only two people in the room so to speak. TARP is a very bad example though, because none of the leading policy theories allow for such a short term process or such a vast information gap. If we can consider the president as part of the legislative process as opposed to an executive agent, i would say legislators are the principal actors. This would be especially true if we only view the 'old' Iron triangle: Legislature, Executive agency, Industry.