One of two Republican lawmakers who attended the meeting, Representative Chris Cannon of Utah, said in an interview afterward that he had pressed Mr. Fielding on whether he “understood that a lie would be prosecutable,” even if the interview was not conducted under oath. “He said, ‘Yes, we understand that,’ ” Mr. Cannon said. Lying to Congress can be a crime even if the false statements are not made under oath.

But Democrats dismissed Mr. Fielding’s offer as window dressing. Senator Harry Reid, the majority leader, suggested that the administration had misled him, and released a Justice Department letter that said it was not aware that Mr. Rove had played any role in the decision to appoint one of his former deputies as United States attorney in Arkansas.

“I want to hear Karl Rove testify under oath about the role he played in this whole affair,” Mr. Reid said.

As the war of words escalated, people on both sides acknowledged a legal fight carried political risks. Beth Nolan, who was counsel to President Bill Clinton and twice testified to Congress under subpoena, said she suspected the clash would lead to more negotiations, and not a court fight. “There’s the legal path to the fight and the political path,” she said. “It’s much more likely that you’ll see a political path.”

The Bush administration has been a fierce defender of presidential powers but has solved most of the issues without going to court. For instance, the president and Vice President Dick Cheney agreed to be interviewed by the commission investigating the Sept. 11 terrorist attacks, although they did so behind closed doors and not under oath. Nevertheless Mr. Bush said Tuesday that he would “oppose any attempts to subpoena White House officials.” Asked if he would be willing to go to court over the matter, Mr. Bush said, “Absolutely.”

Mr. Bush once again defended the dismissals, and he said it was “natural and appropriate” for members of the White House staff to discuss them with the Justice Department. At the same time, he offered an apology to the dismissed United States attorneys, saying, “I regret that these resignations turned into such a public spectacle.”

The motivation for the dismissals is still not fully understood. Democrats, including Senator Charles E. Schumer of New York, who is leading the inquiry in the Senate, and Senator Dianne Feinstein of California, have said they want to know whether prosecutors were dismissed to thwart public corruption investigations.