The beginning of the end for Bush/Cheney?

A response by Senator Leady and Congressman Conyers to White House Counsel Fred F. Fielding concerning the White House's invoking of executive privilege in its refusal to reply to the subpoenas conerning the Attorney firings. This provides insight into the coming actions of Congress against the Executive Branch if (and when) it claims Executive Privilege concerning the subpoenas in the NSA-wiretapping case (served two days ago):

Dear Mr. Fielding:
...We had hoped our Committees’ subpoenas would be met with compliance and not a Nixonian stonewalling that reveals the White House’s disdain for our system of checks and balances.
We urge the President to reconsider this step and withdraw his privilege claim so the American people can learn the truth about these firings. If he is unwilling to withdraw these claims, we call on you to provide more specific information to facilitate ruling on those claims and our consideration of appropriate action to enforce our subpoenas. [...]
Our Committees rejected your "take it or leave it" offer of off-the-record, backroom interviews and severe limits on the scope of our requests as unacceptable, more than three months ago. Since that time, despite our many attempts to narrow the dispute and begin to obtain the information we need, you have not made any effort to work with us on a voluntary basis. Even now, in response to subpoenas authorized by our Committees, you have again merely restated your initial, unacceptable offer. Your proposal is not commensurate with our exercise of the broad investigatory power of Congress. [...]
Please provide the documents compelled by the subpoenas without further delay. If you continue to decline to do so, you should immediately provide us with the specific factual and legal bases for your claims regarding each document withheld via a privilege log as described above and a copy of any explicit determination by the President with respect to the assertion of privilege. You have until July 9, 2007, at 10 a.m. to bring this and any other information you wish to submit to our attention before we move to proceedings to rule on your claims and consider whether the White House is in contempt of Congress.
We were disappointed that we had to turn to these subpoenas in order to obtain information needed by the Committees to learn the truth about these firings and the erosion of independence at the Justice Department. We are even more disappointed now with yet further stonewalling.
Whether or not we have the benefit of the information we have directed you to provide by July 9, we will take the necessary steps to rule on your privilege claims and appropriately enforce our subpoenas backed by the full force of law.
Sen. Patrick Leahy, D-VT, Rep. John Conyers, D-MI