The White House and Congress moved closer to a historic court battle over executive privilege after President Bush refused to meet a Monday deadline for information in the Congressional investigation into the firing of nine U.S. attorneys last year.

President Bush has claimed executive privilege to deny Congressional investigators access to White House aides and documents relating to the firings of U.S. attorneys, and he refused Monday to produce a log of documents being withheld and a legal rationale for each one.

White House counsel Fred Fielding sent letters to House Judiciary Chairman John Conyers (D-Mich.) and Senate Judiciary Chairman Patrick Leahy (D-Vt.) complaining about the tone and basis of their request.

“We are aware of no authority by which a congressional committee may ‘direct’ the executive to undertake the task of creating and providing an extensive list of every document covered by an assertion of executive privilege,” Fielding said.

Fielding added that the rationale for withholding the information was clear: to protect the president’s authority to appoint and remove U.S. attorneys and “to protect a fundamental interest of the presidency: the necessity that a president receive candid advice from his advisors and that those advisors be able to communicate freely and openly with the president, with each other, and with others inside and outside the Executive Branch.”

Fielding said the president would continue to assert executive privilege to attempt to shield former White House counsel Harriet Miers and former White House aide Sara Taylor from Congressional subpoenas. The Senate Judiciary Committee is scheduled to hear testimony from Taylor on Wednesday, while Miers has been called to appear before the House Judiciary Committee on Thursday.

Conyers and Leahy quickly released statements blasting the move.

“While we remain willing to negotiate with the White House, they adhere to their unacceptable all-or-nothing position, and now will not even seek to properly justify their privilege claims,” Conyers said, making it clear that they were prepared to go to court. “Contrary to what the White House may believe, it is the Congress and the Courts that will decide whether an invocation of Executive Privilege is valid, not the White House unilaterally.”

Leahy reiterated that he hopes to negotiate “a workable solution” but decried the White House’s attempt to shield staffers and other information from public view.

Fielding reiterated that the president remained willing to provide information in the absence of subpoenas — under White House-approved conditions — but that offer has been rejected by the Democratic chairmen as insufficient.

“What is the White House trying to hide by refusing to turn over evidence it was willing to provide months ago as long as that information was shared in secret with no opportunity for Congress to pursue the matter further?” Leahy asked. “There is clear evidence that Ms. Taylor was one of several White House officials who played a key role in these firings and the Administration’s response to cover up the reasons behind them when questions first arose.”

Senate Judiciary ranking member Arlen Specter (R-Pa.) also said on the Senate floor that he hoped a deal could still be reached to avoid what he said would be a two-year court battle that would extend past Bush’s leaving office. Specter said the investigation was important because it could “lead us to a new attorney general” and said he would be willing to go along with the White House’s offer of private, informal discussions with Miers and Taylor, but he added that he would prefer a public transcript and said Congress should retain the right to subpoena.

The battle over executive privilege also moved to a second front, as Conyers sent a letter to Bush asking him to waive executive privilege with regard to his decision to spare Vice President Cheney’s former chief of staff, Scooter Libby, from prison. Conyers noted that former President Bill Clinton did so in the case of the pardon of financier Marc Rich in 2001 and that President Gerald Ford testified himself before the Judiciary Committee to defend his pardon of Richard Nixon.

“While I recognize that the clemency power is a Presidential prerogative, your decision to commute Scooter Libby’s sentence has proven highly controversial, with commentators suggesting that this act may have had the effect of removing any further incentive that Mr. Libby may have had to provide more complete information about the leak of information on Valerie [Plame] Wilson’s work as an intelligence agent and the role that your Vice President and you yourself may have played in that leak,” Conyers wrote.

Conyers said he wanted to know what role Cheney played in the decision and on what basis Bush considered Libby’s 30-month prison sentence for perjury and obstruction of justice “excessive.” Conyers also said in the letter that he wanted to know whether Libby had been given assurances either before or after his false testimony that he would be protected from jail time.

“We have received the letter, and will respond appropriately,” wrote White House spokesman Tony Fratto in an e-mail. “It’s notable that Chairman Conyers concedes that his request would require the president to waive executive privilege. We, of course, share the view that the president is entitled to candid and confidential advice from his aides.”

Conyers will hold a hearing on Wednesday on the Libby case and the pardon power featuring former Ambassador Joseph Wilson and legal experts, with future hearings expected. Leahy said on CNN’s “Late Edition” on Sunday that he may seek to call special prosecutor Patrick Fitzgerald to a hearing on the Libby case but had no plans to call Libby. Leahy said the president and vice president “bought his silence” and by not issuing a full pardon, Libby can still claim his Fifth Amendment privilege against self-incrimination to avoid testifying.