WASHINGTON — I. Lewis “Scooter” Libby sat in the courtroom on the opening day of his trial on federal perjury charges, but it was the credibility of his former boss, Vice President Cheney, and the Bush administration that drew the heaviest scrutiny as the selection of jurors began here yesterday.

The vice president’s former chief of staff, Mr. Libby stands accused of lying to federal investigators and a grand jury about his role following the leak of the identity of a CIA officer, Valerie Plame, to reporters in 2003. A government indictment says Mr. Libby, who resigned from the White House in 2005, made false statements about how he learned of Ms. Plame’s CIA affiliation and about his discussions of her with journalists. Mr. Libby, 56, is not charged with the leak itself, but a conviction could carry years of prison time and a stiff fine.

The outing of Ms. Plame followed the publication by her husband, Joseph Wilson IV, of an editorial critical of the Bush administration’s rationale for invading Iraq, and the specter of the war loomed over the proceedings yesterday. The initial pool of jurors took on the feel of a focus group as U.S. District Judge Reggie Walton and attorneys for the prosecution and defense grilled them on their opinions about the Bush administration, the press, and the decision to go to war with Iraq.

Judge Walton asked the pool of about 60 potential jurors a series of 38 questions — some on standard legal matters and others that sought to discover whether their opinions about Mr. Cheney and other administration officials would prejudice them during a trial. He also asked whether they had known or heard of a list of dozens of potential witnesses, which comprised a veritable “who’s who” of Washington power players, including the vice president, the current and former secretaries of state, Condoleezza Rice and Colin Powell; a former CIA director, George Tenet; the chief political adviser to President Bush, Karl Rove; two former White House press secretaries, Ari Fleisher and Scott McClellan, and prominent journalists, including Tim Russert and Andrea Mitchell of NBC News and Bob Woodward of the Washington Post.

Judge Walton and the attorneys then quizzed the jurors individually, and their responses highlighted the difficulty of selecting an unbiased jury to try such a high-profile case in the nation’s political epicenter. The pool is made up of residents from the District of Columbia, where Democrats outnumber Republicans nine to one.

“I don’t have the highest opinion of him,” one man, a financial analyst, said of Mr. Cheney. He later added: “If I had to rank people based on credibility, I wouldn’t put him at the top of the list.”

The man, who said he had followed the case for the past two or three years, said repeatedly that he wanted to think he could judge the vice president’s testimony impartially, but after probing questions from Judge Walton and the defense, he conceded that that was unlikely. The judge dismissed him from the jury pool.

One woman was dismissed much quicker after she said of the Bush administration, “There is nothing they could say or do that would make me think anything positive about them.”

Another potential juror, a middle-aged woman who said she was a lyric soprano, was asked by the defense how she felt about the Bush administration. “I voted for Bush, if that’s what you’re asking,” she volunteered. She was not excused, but Judge Walton called her comment “gratuitous.”

Another woman professed little knowledge of the case, but she said she did know that Ms. Rice lives on the fifth floor of the Watergate because the potential juror said she cleans apartments there.

The line of questioning on the opening day also offered hints at the trial strategy of the defense. While prosecutors say Mr. Libby lied about conversations he had with journalists in 2003, the defense plans to argue that he was too busy to remember them accurately. Judge Walton asked the potential jurors whether they believed the human memory was like “a tape recorder and therefore all individuals are able to remember exactly what they said and were told in the past.” The lead defense lawyers, William Jeffress and Theodore Wells Jr., pressed the point in one-on-one questioning, and in a positive sign for Mr. Libby, none of the potential jurors indicated that they thought human memory was perfect.

Special prosecutor Patrick Fitzgerald, the U.S. attorney in Chicago, is trying the case for the government. He objected several times, with little success, to the questions asked by the defense, saying he feared they were “pretrying” the case.