Mueller was not in the hospital room at the time of the dramatic March 10, 2004, confrontation between then-Attorney General John Ashcroft and presidential advisers Andy Card and Gonzales, who was then serving as White House counsel. Mueller told the House Judiciary Committee he arrived shortly after they left, and spoke with the ailing Ashcroft.
This comes in the wake of Senate Democrats calling for a perjury investigation against Gonzales on Thursday and subpoenaing top presidential aide Karl Rove in a deepening political and legal clash with the Bush administration.
"It has become apparent that the attorney general has provided at a minimum half-truths and misleading statements," four Democrats on the Senate Judiciary Committee wrote in a letter to Solicitor General Paul Clement.
They dispatched the letter shortly before Sen. Patrick Leahy, D-Vt., announced the subpoena of Rove, the president's top political strategist, in remarks on the Senate floor. The White House has claimed executive privilege to block congressional demands for documents or testimony by some current and former presidential aides. President Bush, meanwhile, has continued to support Gonzales.
Sen. Arlen Specter, R-Pa., traveling with Mr. Bush on Thursday, said the backing stems from the president's personal loyalty to Gonzales, a longtime friend.
Democrats issued a laundry list of examples of what one called Gonzales' "lying" before Congress.
"We have now reached a point where the accumulated evidence shows that political considerations factored into the unprecedented firing of at least nine United States Attorneys last year," said Leahy, chairman of the Senate Judiciary Committee.
Gonzales is at the center of the U.S. Attorney controversy, but the call for a perjury probe involved alleged conflicts between testimony he gave the Judiciary Committee in two appearances, one last year and the other this week. The issue revolves around whether there was internal administration dissent over the president's warrantless wiretapping program.
Also at issue, the Democrats said, is a conflict between Gonzales' testimony that he had not spoken with other witnesses about the firings and his former White House liaison's account of an "uncomfortable" conversation" in which the attorney general reviewed his recollection of the events and asked her opinion.
"There's no wiggle room," said Sen. Charles Schumer, D-N.Y., one of the four lawmakers to sign the letter. "It's not misleading. Those are deceiving. Those are lying."
And Senate Majority Leader Harry Reid, D-Nev., told reporters, "I'm convinced that he's not telling the truth," based on conversations with Democrats on the Judiciary Committee.
As for the firing of the prosecutors, e-mails released by the Justice Department show Gonzales' aides conferred with Rove on the matter.
Leahy also said he was issuing a subpoena for J. Scott Jennings, a White House political aide. The deadline for him and Rove to comply was set as Aug. 2.
"For over four months, I have exhausted every avenue seeking the voluntary cooperation of Karl Rove and J. Scott Jennings, but to no avail," the Vermont lawmaker said. "They and the White House have stonewalled every request. Indeed, the White House is choosing to withhold documents and is instructing witnesses who are former officials to refuse to answer questions and provide relevant information and documents."
In response to the Senators' letter, White House spokesman Tony Fratto said, "Every day congressional Democrats prove that they're more interested in headlines than doing the business Americans want them to do. And Americans are now taking notice that this Congress, under Democratic leadership, is failing to tackle important issues," he said.
The call for a perjury investigation marked yet another complication for Gonzales, whose fitness to serve has been bluntly criticized by Republicans and Democrats alike.
In a separate letter Thursday to Gonzales, Leahy said he would give the attorney general eight days to correct, clarify or otherwise change his testimony "so that, consistent with your oath, they are the whole truth."
In their letter to Clement, the four senators wrote that Gonzales' testimony last year that there had been no internal dissent over the president's warrantless wiretapping program conflicted with testimony by former Deputy Attorney General James Comey and with Gonzales' own statements this week before the Judiciary Committee.
They also said Gonzales falsely told the panel that he had not talked about the firings with other Justice Department officials. His former White House liaison, Monica Goodling, told the House Judiciary Committee under a grant of immunity that she had an "uncomfortable" conversation with Gonzales in which he outlined his recollection of what happened and asked her for her reaction.
"The attorney general should be held to the highest ethical standards," the senators wrote.
Clement would decide whether to appoint a special prosecutor because Gonzales and outgoing Deputy Attorney General Paul McNulty have recused themselves from the investigation that involves them. The Justice Department's No. 3 official, Associate Attorney General William Mercer, is serving only in an acting capacity and therefore does not have the authority to do so.