WASHINGTON – President Bush ordered his former White House counsel, Harriet Miers, to defy a congressional subpoena and refuse to testify Thursday before a House panel investigating U.S. attorney firings.

“Ms. Miers has absolute immunity from compelled congressional testimony as to matters occurring while she was a senior adviser to the president,” White House Counsel Fred Fielding wrote in a letter to Miers’ lawyer, George T. Manning.

Manning, in turn, notified committee chairman John Conyers, D-Mich., that Miers would not show up Thursday to answer questions about the White House role in the firings of eight federal prosecutors over the winter.

Conyers, who had previously said he would consider pursuing criminal contempt citations against anyone who defied his committee’ subpoenas, revealed the letters after former White House political director Sara Taylor testified Wednesday before the Senate Judiciary Committee.

Taylor said she knew of no involvement by the president in the firings of the U.S. attorneys.

She irked senators by refusing to answer many questions from a panel investigating whether the firings were politically motivated. She said she was bound by Bush’s position that White House conversations were protected by executive privilege.

Conyers said of Miers, Bush’s former White House lawyer, “As a former public official and officer of the court, Ms. Miers should be especially aware of the need to respect legal process, and we expect her to appear before the committee tomorrow as scheduled.”

Fielding said the Justice Department had advised the White House that Miers had absolute immunity from compelled congressional testimony.

“The president has directed her not to appear at the House Judiciary Committee hearing on Thursday, July 12, 2007,” Fielding wrote.

Across the Capitol a Senate committee spent Wednesday grilling a second reluctant Bush aide about the White House role in the firings.

Unlike Miers, Taylor showed up and haltingly tried to satisfy both the subpoena compelling her testimony and Bush’s executive privilege order not to reveal internal White House discussions.

“I did not speak to the president about removing U.S. attorneys,” Taylor said under stern questioning by Sen. Patrick Leahy, D-Vt., the Senate Judiciary Committee’s chairman. “I did not attend any meetings with the president where that matter was discussed.”

When asked more broadly whether Bush was involved in any way in the firings, Taylor said, “I don’t have any knowledge that he was.”

She quickly found out what Miers might have already known: It’s almost impossible to answer some questions but not others without breaching either the subpoena or Bush’s executive privilege claim.

“I have not done a great job at that,” Taylor said of the predicament at one point. “I have tried.”

Sen. Arlen Specter, R-Pa., said that may not be enough to protect her from a contempt citation.

“There’s no way you can come out a winner,” said Specter, the panel’s senior GOP member and also its former chairman. “You might have been on safer legal ground if you’d said absolutely nothing.”

As for the prospects of pursuing a criminal citation for contempt of Congress, Leahy said, “That’s a decision yet to be made.”