(adds reaction beginning in 10th paragraph) By Andy Sullivan WASHINGTON, Feb 13 (Reuters) - U.S. Vice President Dick Cheney will not testify as expected in a former top aide's perjury trial that has exposed White House efforts to counter Iraq-war critics, the aide's lawyers said on Tuesday. Defendant Lewis "Scooter" Libby, Cheney's former chief of staff, likewise will not take the witness stand, his lawyers said as they abruptly prepared to wrap up their case on Wednesday. Cheney had said that he expected to testify in the trial, creating the prospect of a top Iraq-war architect answering questions under oath about the White House's campaign to justify the war. Libby is charged with lying to investigators as they sought to determine who leaked the identity of a CIA analyst to reporters in 2003, after her husband accused the Bush administration of hyping Iraq's nuclear ambitions to bolster its case for invasion. Prosecution witnesses have portrayed a White House focused on discrediting Plame's husband, former ambassador Joseph Wilson, at a time when the public was beginning to question the rationale for the Iraq war. Libby's lawyers say he did not lie to the FBI and a grand jury, but simply misremembered conversations he may have had about CIA operative Valerie Plame because he was preoccupied with national security matters. Libby's silence makes the testimony of his successor at the vice president's office all the more crucial. John Hannah, Cheney's current national security advisor, told the court earlier on Tuesday that Libby frequently forgot conversations over the course of a single day. "On certain things Scooter just had an awful memory," Hannah said. "I would say, 'Yeah, that's a great idea because I told you this morning." Legal experts said the defense team probably decided that it was too risky to have Cheney and Libby testify. Cheney would have brought plenty of baggage along with the prestige of the White House to the witness box, said former U.S. prosecutor Robert Mintz. "To the extent that this trial becomes a referendum on the administration's Iraq policy, that could hurt Libby's chances," Mintz said in an e-mail. Jurors have already heard an eight-hour recording of Libby's grand-jury testimony. On the witness stand, prosecutors would force him to explain why his version of events differs from that of other witnesses, said Scott Fredricksen, a former government lawyer. George Washington University law professor Jonathan Turley said the defense appeared to be struggling. "Most jurors expect defendants to testify, and the failure to do so can lead to silent presumptions against them on credibility questions," Turley said in an e-mail.
