Judge Robert H. Bork came under increased pressure yesterday over the issue of whether he is deliberately softening some of his controversial stands to win confirmation to the Supreme Court from a deeply divided Senate.

As that theme emerged on the third day of hearings before the Senate Judiciary Committee, Bork and his Republican allies on the committee and in the Reagan administration complained that after weeks of portrayal as a rigid, conservative ideologue, he is now accused of being, as one put it, "dangerously flexible."

"I've been getting criticism because I never change my mind and now because I changed my mind," Bork said while explaining his evolving views on First Amendment protections.

But Sen. Patrick J. Leahy (D-Vt.) bluntly told Bork that the issue of whether he is undergoing a "confirmation conversion" before the committee "is going to be a question."

Sen. Arlen Specter (R-Pa.), considered one of three swing votes on the committee, traced some of Bork's evolving positions, calling them "pronounced shifts," and added:

"The concern I have is where's the predictability in Judge Bork. Where's the assurances for this committee and the Senate of where you'll be?"

The Leadership Conference on Civil Rights also attacked Bork's credibility, distributing a seven-page document entitled "Bork v Bork." The document contrasted excerpts from Bork's testimony before the Judiciary Committee this week with earlier statements he has made on the same subjects.

"What the New Judge Bork now says differs significantly from the Old Judge Bork on free speech, discrimination on the basis of sex, privacy and contraception," the Leadership Conference said in a statement. "The New Judge Bork has made statements in favor of the civil rights laws, and against restrictive covenants and forcible sterilization, which the Old Judge Bork, in all of his voluminous writings and speeches, never wrote or uttered."

The statement added that Bork's earlier writings, when he "had little incentive to recast his views in a manner likely to be more palatable to the Senate, are a truer indication of what Judge Bork would do if he became a member of the Supreme Court."

Tom Korologos, a private lobbyist brought in by the White House to help win Bork's confirmation, accused Bork's opponents of "grasping at straws."

"Look at these guys up here," Korologos said, gesturing toward the committee members. "How many times have they changed their minds? Don't you want a living, flowing judge, rather than a predictable, dead one?"

As the interrogation over often arcane points of law droned on, a sense of weariness settled over the Senate Caucus Room. A rare moment of drama came late in the day and involved not Bork's legal philosophy but the death of his first wife, Claire, in 1980 after a long fight with cancer.

Leahy had questioned Bork about outside consulting fees of $200,000 a year or more that he earned while a professor at Yale Law School from 1979 to 1981.

"Those were the only years I made money," Bork said. "There was a reason I made money, but I don't want to go into it here."

Leahy said he understood the reasons and that the consulting fees were proper. But Sen. Gordon J. Humphrey (R-N.H.), one of Bork's strongest supporters, then asked Bork if the consulting work "coincided with heavy medical bills in your family."

Bork put his hand to his face and appeared close to tears.

"Yeah," he said in a muffled voice.

"I think it's time we stopped," Committee Chairman Joseph R. Biden Jr. (D-Del.) interjected, calling a recess in the hearings.

Bork, 60, a judge on the U.S. Court of Appeals here since 1982, has a prolific, 25-year record of writings and statements on numerous legal and political issues. Many of his positions have been highly controversial and his opponents hope to turn these against him to defeat his nomination.

By yesterday, however, it appeared that Bork and his allies were less concerned about the controversial views he has reaffirmed during the hearings than by the skeptical suggestions that he was shading other positions to win Senate votes.

Bork was questioned extensively about his statement Wednesday that he no longer viewed as "fundamentally wrong" a 1969 Supreme Court ruling that language advocating law-breaking was protected by the Constitution as long as there was no danger of "imminent lawless action."

"I haven't changed my mind on what I said on this subject," Bork insisted. He said that as a theoretical matter he still might criticize the decision but that "as a judge, I accept it."

Bork repeatedly referred to issues as being "settled law," attempting to assure the committee that he would uphold precedents that he stridently criticized as a law professor.

"There is now a vast corpus of First Amendment decisions that I accept as law," he said. "I have no desire to disturb that body of law."

But Specter and Sen. Dennis DeConcini (D-Ariz.), another undecided member of the committee, continued to express skepticism. Both said the hearings were the first time they had ever heard Bork say he would extend the equal protection guarantees of the 14th Amendment to "all people," including women and other groups of citizens.

Previously, Bork has insisted that these protections should apply only to racial and ethnic groups.

"There is a considerable difference in what he has written about as a professor and what he said today," Specter said. "He said he would apply the law in a very different way than he has written about."

Asked about the "confirmation conversion" allegations, Sen. Howell Heflin (D-Ala.), said, "That's a legitimate area of consideration."

DeConcini said that from the testimony, he did not consider Bork "predictable" as a potential Supreme Court justice and that this bothered him "a lot."

In response to the skeptical questioning, Bork insisted that he was not shifting his longstanding, fundamental stands on the role of judges, the proper interpretation of the Constitution and numerous specific legal issues.

"Let me speak to this issue of confirmation conversions," he said. "I have got a lot of positions I've taken in the past that I've reaffirmed here which I have not converted."

He said it is not uncommon for people to change their political views but that his bedrock judicial philosophy remained consistent.

Bork several times yesterday said he is "about where the Supreme Court is" in areas where he has repeatedly attacked their decisions, including free speech, obscenity, sex discrimination and the general guarantees of due process and equal protection.

Specter, DeConcini and Heflin -- the three undecided votes -- remained the focus of attention yesterday as Bork's supporters and critics on the committee continued to hammer away from their well-established positions.

Sen. Edward M. Kennedy (D-Mass.), Bork's most outspoken opponent, led him through a discussion of his criticisms of cases dealing with the balance of power between the executive and legislative branches of the federal government.

Bork's critics, citing his earlier comments on issues such as the War Powers Resolution, judicial oversight of intelligence activities and the constitutionality of independent prosecutors, charge that he has a strong bias in favor of executive power.

Kennedy sought to establish this point, accusing Bork of viewing members of Congress as "second-class citizens" and of interpreting the concept of checks and balances as "the president has a blank check."

In his most direct criticism of a member of the committee, Bork retorted that Kennedy had made a "most unfair characterization of my views."

The exchange, however, was somewhat stilted as Bork held his apparent irritation in check and Kennedy read from a statement, ending each section by asking if Bork had "ever expressed a different view in public" from his earlier statements.

Kennedy was not the only committee member to work from a script. Sen. Orrin G. Hatch (R-Utah) led Bork through a carefully crafted review of his record on civil rights.

"Is there a single time you have advanced a position that was less sympathetic to the rights of minorities and women than that adopted by the Supreme Court or Justice {Lewis F.} Powell?" whom Bork would replace on the high court if confirmed, Hatch asked.

"There is no such case," Bork replied.

Hatch cited a number of cases in which Bork took positions that angered conservatives, saying he had "stood tall against ideology." He said "rigid, radical groups" were attempting to destroy Bork's reputation and that viewers of the hearings "will be as disgusted as I am."

Sen. Alan K. Simpson (R-Wyo.) also rushed to Bork's defense on the issue of his evolving positions on certain issues.

"We are judging what you did by how we feel about America now," he said. "These are different times than in 1964 at the time of the Civil Rights Act."

Bork once harshly criticized the public accommodations section of the 1964 Civil Rights Act, a position he long ago abandoned and which he has defended during the hearings by noting that a large number of southern senators also opposed the measure at the time of its passage.

Bork is expected to complete his marathon testimony before the committee today.