The Senate Judiciary Committee began preparations yesterday for a protracted battle over the nomination of U.S. Appeals Court Judge Robert H. Bork to the Supreme Court amid clear signs that his potential impact on the court's ideological "balance" will be the focal point of a liberal Democratic assault on the nomination.

Committee Chairman Joseph R. Biden Jr. (D-Del.) said he expects to soon name a panel of "distinguished legal scholars" to review Bork's court decisions and other writings as a first step in what is widely predicted to be a long and possibly bitter confirmation process.

A date for the beginning of committee hearings has not been set. It may be difficult to begin the hearings before Congress' August recess, but Peter F. Smith, a spokesman for the committee, said the possibility has not been ruled out.

Smith said Biden plans to meet Tuesday with fellow Judiciary Committee Democrats to discuss timing and other aspects of the confirmation process.

Meanwhile, initial reactions to the nomination by leading Senate Democratic liberals indicate that Bork's role as the prospective replacement for retired justice Lewis F. Powell Jr., who often was the critical fifth vote in court decisions, will be a key factor in the confirmation fight.

Biden cited this issue in explaining his comment last fall that if President Reagan nominated Bork and nothing was found in his background to raise serious questions about his fitness, "I'd have to vote for him."

Faced with the reality of Bork's nomination, Biden said he would support Bork as a replacement for one of the court's conservative justices, among them Antonin Scalia, whose nomination was approved without dissent by the Judiciary Committee and the full Senate last fall.

But, Biden added, "I would attempt to have diversity on the bench. I would see to it that there was a Scalia on the bench and a {liberal Justice William J.} Brennan on the bench . . . . It is wrong to send someone to tip the balance."

Interviewed last night on the Cable News Network program "Crossfire," Biden said what is at stake in the Bork nomination is "the direction of the country on social issues."

"This is a fundamental swing vote on the court," he said.

Two other Judiciary Committee Democrats used almost identical language in questioning the Bork nomination.

In a sweeping condemnation of Bork's record and views, Sen. Edward M. Kennedy (D-Mass.) said, "In the current delicate balance of the Supreme Court, his rigid ideology will tip the scales of justice against the kind of country America is and ought to be."

Sen. Howard M. Metzenbaum (D-Ohio) said he does not question Bork's "professional qualifications," but added, "That doesn't mean he's qualified to be the swing vote on the Supreme Court."

Asked whether Bork should be held to "a higher standard" because of the critical role Powell played in a number of major cases, Metzenbaum replied, "The answer is yes."

With the possible exception of Sen. Arlen Specter (R-Pa.), the Judiciary Committee's six Republicans appear all but certain to line up behind the Bork nomination. The committee's eight Democrats are dominated by liberals such as Biden and Kennedy, making the more conservative Sens. Dennis DeConcini (D-Ariz.) and Howell Heflin (D-Ala.) the key swing votes.

Unlike some other committee Democrats who have said they have serious reservations about Bork's conservative philosophy, DeConcini said, "I do not apply ideological standards to a nominee."

Senate Majority Whip Alan Cranston (D-Calif.) said it is "quite possible" that Bork's nomination could be rejected by the committee but that such action probably would not end the confirmation process.

Biden said "the real fight is going to take place on the floor of the Senate." Senate Majority Leader Robert C. Byrd (D-W.Va.) also indicated that, regardless of the committee vote, the issue will be decided by the full Senate.

"I hope this nomination will have its day in court in the full Senate," he said. Staff writer Dan Balz contributed to this report.