WASHINGTON - Two potential jurors who expressed negative views of Bush administration officials were dismissed on the opening day of the perjury trial of former White House aide I. Lewis "Scooter" Libby.

Yesterday's start of jury selection in the CIA leak case provided a potentially crucial victory for Libby's lawyers. They were allowed to ask potential jurors in detail about their opinions of the administration, Vice President Cheney, and a group of high-profile reporters, and whether the administration had lied to push the country into war with Iraq.

The defense faces a key challenge in picking a jury for this highly political case in a city where registered Democrats outnumber Republicans by more than 9-1. Cheney is expected to be a defense witness.

Special prosecutor Patrick J. Fitzgerald objected repeatedly, but to no avail, that Libby's lawyers were going beyond the more general opinion questions that U.S. District Judge Reggie Walton asked the entire jury pool when proceedings began yesterday morning.

Fitzgerald argued that defense attorneys Theodore Wells and William Jeffress were "trying the case" in jury selection. But Walton ruled that the defense had a right to know if "somebody has a very negative attitude to the Bush administration."

Libby, who was an adviser to President Bush and chief of staff to Cheney, is accused of lying to investigators about his conversations with reporters regarding the public disclosure of CIA officer Valerie Plame Wilson's name. Her identity was leaked to reporters in 2003 after her husband, former Ambassador Joseph Wilson, publicly accused the Bush administration of trying to push the nation into war by knowingly repeating a false story about Iraq's trying to obtain uranium in Africa for nuclear weapons.

Yesterday's biggest defense success came during extended questioning of a young financial analyst who had read about the case. He said that he didn't have the highest opinion of Cheney, and that "if I had to rank people as to credibility, I wouldn't put him at the top of the list."

Wells, Fitzgerald and Walton each repeatedly tried to see whether the analyst could put those views aside in weighing trial evidence, but the man finally acknowledged that Cheney would have a strike against him in a credibility dispute with other witnesses. So Walton excused him for cause.

By comparison, one young woman swiftly sealed her own disposition by announcing right off the bat that she was "completely without objectivity" and that there was nothing that administration officials "could say or do that would make me think anything positive about them."

Libby broke into a half smile and shot a glance at his wife in the first row of spectators as Walton sent the woman home.

Six jurors were qualified to serve yesterday. Once that number reaches about three dozen, the judge will allow lawyers to exercise their peremptory strikes. The defense has 12 such challenges and prosecutors eight. Walton intends to seat 12 jurors and four alternates.

Walton said the trial should last four to six weeks.

Wells told Walton that the case would begin with, and concentrate on, Joseph Wilson's criticisms of how the Bush administration justified the war. Wilson has argued that the leak of his wife's CIA identity was designed to punish him and silence other administration critics in the intelligence agencies.

No one has faced charges for the leak itself.