Ms. Taylor was ordered to appear before the Senate committee on July 11. Ms. Miers, who was briefly a nominee for Supreme Court justice, was told to appear before the House panel the following day.

The committees had already voted to authorize such subpoenas, so it was not surprising that they decided today to go ahead and issue them. Still, the action stepped up the political confrontation over the dismissals, and over the general performance of Attorney General Alberto R. Gonzales and the state of the Justice Department.

So far, the White House has said it will not make any current or former officials available to testify before the panels on the matter except in private interviews, with no transcripts kept. The lawmakers have disdained that arrangement as unacceptable.

"By refusing to cooperate with Congressional committees, the White House continues its pattern of confrontation over cooperation, and those who suffer most in this case are the public and the hard-working people at the Department of Justice," Senator Patrick J. Leahy of Vermont, chairman of the Senate committee, said in a statement today.

Representative John D. Conyers of Michigan, the chairman of the House committee, said the subpoenas were "a demand on behalf of the American people."

"The breadcrumbs in this investigation have always led to 1600 Pennsylvania," Mr. Conyers said, referring to the White House by its street address. "This investigation will not end until the White House complies with the demands of this subpoena in a timely and reasonable manner, so that we may get to the bottom of this."

The White House reacted quickly today to the subpoenas, arguing that the committees could easily obtain all the facts they need through interviews and relevant documents, but that the Democratic chairmen "are more interested in drama than facts," as Dana Perino, a White House spokeswoman, put it in an exchange with reporters.

The latest development follows the Senate Democrats’ attempt to pass a symbolic "no confidence" resolution against Mr. Gonzales. That attempt was thwarted on Monday when Mr. Gonzales’s critics fell seven votes short of the 60 needed to clear a procedural hurdle. That effort, too, was dismissed by the White House as a publicity stunt.