political allies have raised at least $3.5 million to defend him, said a source close to Libby who s

The defense's central theory is that Libby suffered from a notoriously bad memory and misspoke to investigators about his role in the Bush administration's disclosure of the identity of undercover CIA officer Valerie Plame. The decision to foreshorten the case means that jurors will hear little testimony and see scant evidence to back that contention. Yesterday, John Hannah, a former deputy to Libby for national security matters, provided the sole support for the idea, testifying that "on certain things, Scooter just had an awful memory."

The decision also means that the defense will not call any witnesses to explicitly buttress a dramatic assertion by lawyer Theodore V. Wells Jr. in his opening statement to the jury: that Libby was scapegoated by his White House colleagues when the leak investigation began.

Outside legal specialists said that Libby's attorneys appear to have concluded that the risks of exposing the defendant and the vice president to cross-examination on the witness stand outweighed the benefits they could provide in establishing Libby's innocence. Cheney would have been the first sitting vice president to testify in a criminal trial in at least a century.

"You can't control how things are going to go," said Randall Eliason, a former chief prosecutor of white-collar crimes for the U.S. Attorney's Office in Washington. Eliason said that Special Counsel Patrick J. Fitzgerald could have grilled Libby about any conflicting statements he had made.

Eliason and Carl Tobias, a University of Richmond law professor, said that Libby's defense team is experienced and must be confident that it has established reasonable doubt in cross-examination of prosecution witnesses. In closing arguments, they predicted, defense lawyers may remind jurors about holes they poked in other witnesses' accounts -- and what they may portray as a lack of clear evidence that Libby deliberately lied.

"It's a pretty tepid defense that's been mounted, and I wouldn't even say mounted," Tobias said. "There was all this information to suggest the defense was going to put on more of a defense than we saw."

Libby's attorneys did not publicly explain why they decided that the two men should not testify. For the past several days, however, they had been laying groundwork for a possible change in course, filing court papers and repeatedly asking U.S. District Judge Reggie B. Walton to permit them to preserve the faulty-memory defense even if they chose not to call Libby as a witness.

Yesterday afternoon, just before the jury was excused for the day early because of an approaching winter storm, Wells told Walton that the defense team had just decided that it would "release" Cheney as a possible witness.

Wells also said that he and Libby's defense team had just recommended to Libby that he not testify on his own behalf. After conferring with his wife, also a lawyer, Libby accepted his counsel's advice, Wells said.

Walton then asked Libby whether he was certain that he wanted to forgo his right to testify. "Yes, sir," he replied in a quiet, steady voice, speaking in court for the first time since his trial began.

Libby is charged with five felonies: two counts of making false statements to FBI agents, two counts of perjury before a grand jury and one count of obstructing the CIA leak investigation. He is not charged with the leak itself.

Prosecutors contend that Libby lied to obscure the fact that he had improperly shared classified information with reporters as he played a key role in an effort by the Bush administration to discredit Plame's husband. The CIA officer is married to former ambassador Joseph C. Wilson IV, who was sent to Niger by the CIA in 2002 to explore reports that Iraq had sought to buy nuclear material there. He concluded that the reports were not true.

Early in the summer of 2003, Wilson wrote a stinging critique of President Bush and the Iraq war, accusing the White House of twisting his conclusions to justify the invasion. Prosecutors contend that Libby told several reporters that Wilson's wife worked at the CIA to suggest that he had been sent on the mission as a result of nepotism, not because of his expertise.

The defense counters that when Libby met with FBI agents and grand jurors, he innocently misremembered his conversations with journalists, because they were insignificant amid his pressing work on national security matters.

Since shortly after Libby's October 2005 indictment, friends and political allies have raised at least $3.5 million to defend him, said a source close to Libby who spoke on the condition of anonymity because the fund is private.

The other defense witnesses to appear so far were a former State Department official and seven journalists. Six of the reporters testified Monday that Libby had not told them about Plame.

Yesterday, Hannah, now the vice president's national security adviser, highlighted points that Cheney and Libby might have offered if they had testified. Hannah said that Libby essentially had two full-time jobs and, under questioning by defense attorney John Cline, gave the jury a tour of complex and sensitive foreign-policy issues in which Libby was immersed from May 2003 to March 2004. That period is significant, because it began when Cheney first told Libby about Plame and ended with his appearances before the grand jury investigating the leak of her identity.

Like Libby, Cheney faced the possibility of awkward questions from prosecutors had he appeared as a witness. Several prosecutors -- and Libby himself in his grand jury testimony -- have portrayed Cheney as deeply involved in the White House effort to discredit Wilson. Jurors have heard audiotape of Libby telling the grand jury that he and Cheney may have discussed whether to mention Plame to reporters but that he was not certain.

From the start, the defense repeatedly said that Libby and Cheney probably would take the stand. Potential jurors were asked their opinion of Cheney, and those with strongly negative views of him were not chosen. Before the trial, defense lawyers had told Walton that Libby would testify, and that persuaded the judge to let the defense note during the trial the crush of national security issues Libby was handling.

At various points in the trial, defense attorneys indicated that they might call as witnesses several other people they later decided to abandon. They include Karl Rove, the White House senior adviser; Dan Bartlett, counselor to the president; Jack Eckenrode, the former FBI agent in charge of the case; Colin L. Powell, former secretary of state; and Eric Edelman, Libby's former deputy.

After announcing that Libby and Cheney would not testify, defense attorneys said their last witnesses today would be CIA employees who regularly briefed Libby about national security matters and could amplify Hannah's testimony about the world crises Libby was juggling around the time of the CIA leak. Prosecutors are seeking to block the briefers' testimony.