Few problems knife, one - Congress has no power to subpoena White House officials who work in the Executive Office of the President. That's due to the Constitution of the USA.
---Executive privilege may properly be asserted in response to a congressional subpoena seeking testimony by the Counsel to the President concerning the performance of official duties on the basis that the Counsel serves as an immediate adviser to the President and is therefore immune from compelled congressional testimony.
That is the conclusion of a Department of Justice brief on the subject prepared for President Clinton by Attorney General Janet Reno and dated September 16, 1999. Here's some more:
Advice to the President and other deliberative communications and materials fall within the scope of executive privilege. See generally United States v. Nixon, 418 U.S. 683, 705-13 (1974); Nixon v. Administrator of General Services, 433 U.S. 425, 446-55 (1977). The Supreme Court has recognized
the necessity for protection of the public interest in candid, objective, and even blunt or harsh opinions in Presidential decisionmaking. A President and those who assist him must be free to explore alternatives in the process of shaping policies and making decisions and to do so in a way many would be unwilling to express except privately. These are the considerations justifying a presumptive privilege for Presidential communications. The privilege is fundamental to the operation of Government and inextricably rooted in the separation of powers under the Constitution.
United States v. Nixon, 418 U.S. at 708. It is thus well established that not only does executive privilege apply to confidential communications to the President, but also to "communications between high Government officials and those who advise and assist them in the performance of their manifold duties."---
Read the whole thing from the link below. Also - You find me an honest polititain, I will show you a flying pig.
Honest I will.
http://www.usdoj.gov/olc/falnpotus.htm