Supreme Court nominee Robert H. Bork yesterday ran into a barrage of skeptical questioning by key members of the Senate Judiciary Committee who challenged several of his longstanding positions and questioned how consistent he would be in applying his controversial judicial philosophy.

Under questioning during his second day of testimony before the committee, Bork retracted his earlier stand on some First Amendment issues and appeared to soften his approach to sex-discrimination cases.

But Bork, a judge on the U.S. Court of Appeals here, reaffirmed many other conservative positions, saying for the first time yesterday that he could find no constitutional basis for Bolling v. Sharpe, the 1954 Supreme Court decision that outlawed segregation in the District's public schools at the same time the court, in Brown v. Board of Education, outlawed segregation in the rest of the country. Bork added later that he would never seek to overturn the case.

"I should repeat that segregation is not only illegal but immoral," he said.

Bork's answers during six hours of often lively questioning did not satisfy two of the key swing votes on the Judiciary Committee.

"You leave this senator unsatisfied on how this senator can conclude that you are going to protect the citizens of this country in interpreting the Constitution on the court as it relates to sex," Sen. Dennis DeConcini (D-Ariz.) said. "I am trying to satisfy myself that you are not excluding {from legal protection} large segments of our population," he added.

Sen. Arlen Specter (R-Pa.), another swing vote, told Bork his current positions on some issues leave him "a significant distance" from the doctrine of "original intent," which Bork says is the core of his judicial philosophy.

Bork's most dramatic shift came under questioning by Sen. Patrick J. Leahy (D-Vt.), who is considered virtually certain to oppose confirmation. Asserting that "I simply do not have a narrow view of the First Amendment's protection of freedom of press and speech," Bork said he no longer views as "fundamentally wrong" a 1969 Supreme Court ruling that held that even language advocating law breaking was protected by the Constitution as long as there was no danger of "imminent lawless action."

Asked whether he had ever before voiced this view, Bork replied, "Not in public."

Bork said this was an example of his evolving thinking on free-speech issues. While in 1971 he maintained the First Amendment protected only explicitly political speech, he said yesterday that this was "a dumb idea."

Leahy said later he found Bork's shift on the 1969 court ruling "unbelievable."

"It is a very rapid change from just about every position he's taken on First Amendment rights for nearly 20 years," he said. Leahy added that he wants to question Bork more today to make sure he is not undergoing a "confirmation conversion" on free-speech issues.

Specter, beginning his skeptical line of questioning, also told Bork he was "a little surprised" by the answers given to Leahy.

Sen. Howell Heflin (D-Ala.), another key vote on the committee, also indicated he was looking for some assurance as to how Bork would vote on the high court. "Some of your writings are extreme," Heflin said. "I wish I was a psychiatrist rather than a lawyer" in order to "figure out what you would do if you get on the Supreme Court."

Bork, a former Yale law school professor, said, "the best guide to that is what I have done in any position of responsibility, when I wasn't speculating" in academic writing. "As solicitor general, I carried out my duties in not a speculative or extreme fashion at all. And as a judge on the court of appeals," he said, "I think I have not been extreme in any way."

Yesterday's exchanges were far more lively than the often-stilted proceedings at the opening of the hearings Tuesday. Bork was often animated, occasionally flashing his well-known wit.

On other subjects, Bork:Volunteered that "I am not an agnostic." This was in response to a description of him as an agnostic in Time magazine that has caused some concern, particularly among southern senators, the key voting bloc on the nomination.

This report, Bork said, "arose from the following conversation, and the reporter agrees that it arose from the following conversation. He said, 'You're not terribly religious are you?' And I said, 'Not in the sense you mean.' That's it. He went bang, he's an agnostic."

The Time magazine reporter, David Beckwith, yesterday acknowledged that the word agnostic was his but was "based on what Bork said, plus other people I talked to."

"I'm comfortable with what we said," Beckwith said. Defended his actions as solicitor general when, under orders from President Richard M. Nixon, he fired Watergate special prosecutor Archibald Cox.

"I understood from the beginning that my moral and professional lives were on the line if something happened to those {Watergate} investigations," Bork said. Said that "as a policy matter, any long-run institution of quotas worries me very much." Bork added that it would be improper for him to comment on how he would be likely to rule in affirmative-action cases but said "my policy views don't determine my constitutional views." Sought to assuage the fears of minorities who are strongly opposed to his confirmation.

"If I were a black man and knew my record as solicitor general and a judge, I would not be concerned because my civil rights record is a good one," Bork said. Asked by Sen. Charles E. Grassley (R-Iowa) for assurances that he would not radically change the views he had expressed to the committee if confirmed to a lifetime seat on the court, Bork said:

"For 16 years I have been saying one thing about the courts -- they have to be guided by the intentions of lawmakers, with some respect for precedent. If I got on the Supreme Court and did anything else, I'd be a fool in history. I suppose that's the best guarantee I can give you."

Bork's comments on the District school-desegration case caused an uproar among his opponents, who seized on it to question his likely stands on future civil rights cases.

In a statement, the Leadership Conference on Civil Rights called Bork's statement "astonishing and disturbing" and said that his assurances that he would not seek to overturn Bolling v. Sharpe "is of little comfort."

"Surely the vigor with which Judge Bork would enforce Bolling will be colored by his conviction that Bolling itself is bad law," the group said.

Bork commented on the case during complex questioning by Specter centered on his view of "original intent," the doctrine that holds that judges must adhere strictly to the words and intentions of those who wrote the Constitution or laws.

Bork has long criticized federal judges and the high court as improperly extending constitutional guarantees of due process and equal protection far beyond what the Framers intended.

The Supreme Court's landmark ruling in Brown v. Board of Education was based on the equal protection clause of the 14th Amendment. That clause applies only to actions by state and local governments, not the federal government.

At the time the District schools were under federal jurisdiction, so the high court, in the companion Bolling ruling, used the due process clause of the Fifth Amendment to outlaw segregated schools here. The court, in a unanimous ruling, said "discrimination may be so unjustified" that it violates due process.

Bork has long defended the Brown decision as correctly decided in keeping with the fundamental aim of equal protection. But asked yesterday whether he accepted the constitutional basis for the Bolling ruling, he said, "I haven't thought of a rationale for it."

Specter, suggesting that he found some of Bork's views inconsistent, said it appeared that Bork was willing to stray from the doctrine of original intent in some cases -- such as school-desegregation or interstate-commerce issues that are well established in law and custom -- but not in others.

"What happens to your principle {of original intent}?" Specter asked, saying that he will return to the subject in the next round of questioning.

"I think that what so many of us are looking for," Specter said, "is some assurance of where you are."

DeConcini's questions centered on the application of the equal protection clause to sex-discrimination cases, an application that Bork has criticized in the past. Bork said yesterday he would strike down laws that discriminated against women unless states could show a "reasonable basis" for the laws. In the past, Bork has said that to extend equal protection guarantees to women and other groups would "trivialize" the Constitution.

Responding to DeConcini's expressions of skepticism, Bork defended his record on women's rights, saying that "there is no reason . . . to think that I have any problem protecting women or any other group."

Yesterday's hearing began with Sen. Howard M. Metzenbaum (D-Ohio) attempting to establish that Bork has not been completely candid in recounting his role in the "Saturday Night Massacre" firing of Watergate special prosecutor Cox on Oct. 20, 1973.

Metzenbaum produced documents from the Watergate era he said showed that before Cox was fired Bork, as solicitor general, had actively advised the Nixon White House on how best to exert claims of executive privilege in seeking to withhold evidence from the investigation.

Bork agreed he had given the White House advice on the general area of executive privilege, but said, "I never advised the White House on how to deal with the Watergate special prosecutor's force."

Bork also recounted, as he had in his 1982 confirmation hearing for the court of appeals, the events leading up to the Saturday Night Massacre.

He said that when he realized that Attorney General Elliot L. Richardson and Deputy Attorney General William D. Ruckelshaus were going to resign rather than fire Cox, "it occurred to me that I was third in command at the Justice Department."

"It hit me like a ton of bricks," Bork said, describing how he paced around Richardson's office as he considered whether he could execute Nixon's order.

"I finally said, 'Yes, I can do it, but I will {then} resign,' " Bork said.

But Bork said Richardson and Ruckelshaus urged him not to resign, to instead stay on to protect the integrity of Justice Department operations and the Watergate investigation.

"Elliot and Bill were both quite strong on this," he said.