Washington ? President Bush directed former aides to defy congressional subpoenas Monday, claiming executive privilege and prodding lawmakers closer to their first contempt citations against administration officials since Ronald Reagan was president.

It was the second time in as many weeks that Bush had cited executive privilege in resisting Congress’ investigation into the firings of U.S. attorneys.

White House Counsel Fred Fielding insisted that Bush was acting in good faith in withholding documents and directing the two aides – Fielding’s predecessor, Harriet Miers, and Bush’s former political director, Sara Taylor – to defy subpoenas ordering them to explain their roles in the firings over the winter.

In the standoff between branches of government, Fielding renewed the White House offer to let Miers, Taylor and other administration officials meet with congressional investigators off the record and with no transcript. He declined to explain anew the legal underpinnings of the privilege claim as the chairmen of the House and Senate judiciary committees had directed.

“You may be assured that the president’s assertion here comports with prior practices in similar contexts, and that it has been appropriately documented,” Fielding wrote.

Rep. John Conyers, chairman of the House panel, left little doubt where the showdown was headed.

“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,” the Michigan Democrat said.

Sen. Arlen Specter, R-Pa., said the posturing was a waste of time and money and a distraction from the questions at hand: Who ordered the firings, why, and whether Attorney General Alberto Gonzales should continue to serve or be fired.