The Senate voted 90 to 9 last night to confirm Judge David H. Souter to succeed retired Justice William J. Brennan Jr. on the Supreme Court.

President Bush's first nominee to the court was approved by a strong bipartisan majority despite complaints by some Democrats that Souter's views on many constitutional issues remain a mystery. As a replacement for the court's most powerful liberal voice, the 51-year-old New Hampshire native is expected to play a key role in shaping the court's direction in years to come.

Only liberal Democratic Sens. Brock Adams (Wash.), Daniel K. Akaka (Hawaii), Bill Bradley (N.J.), Quentin N. Burdick (N.D.), Alan Cranston (Calif.), Edward M. Kennedy (Mass.), John F. Kerry (Mass.), Frank R. Lautenberg (N.J.) and Barbara A. Mikulski (Md.) voted against confirming Souter as the 105th justice of the court. Sen. Pete Wilson (R-Calif.) did not vote.

Souter, named to the U.S. 1st Circuit Court of Appeals in Boston last spring after serving as attorney general, trial judge and member of the state Supreme Court in New Hampshire, will be sworn in Tuesday morning. The court began its new term Monday.

Souter watched the vote on television in the Concord, N.H., law office of Tom Rath, a close friend from their days in the attorney general's office. In keeping with the cautious demeanor he displayed during his confirmation hearings, Souter was offered a bottle of champagne after the 51st vote in his favor was cast, but according to Rath, wouldn't open it until the final vote was announced.

Later at the state Capitol, Souter said: "I have been given much, and much will be expected from me in return. I will make that return to you and I will make it in the fullest measure that I can."

Although he voted for confirmation, Senate Judiciary Committee Chairman Joseph R. Biden Jr. (D-Del.) said less is known about Souter than any other nominee to the court in a quarter-century, despite what he described as one of the most extensive inquiries into a court nominee the Senate has conducted.

Biden complained in particular about Souter's refusal during his hearings to answer questions about abortion rights, and expressed misgivings about where he stands on key aspects of constitutional law dealing with race and sex discrimination and church-state separation.

Especially on the abortion issue, Souter "frustrated senators and frustrated our ability to exercise one of our constitutional responsibilities, needlessly so," said Biden.

But Biden and other Democrats who voted for Souter indicated they respected his integrity, ability and apparent open-mindedness and were convinced he was not what Biden called a "right-wing, ideological conservative" who would roll back landmark decisions dealing with civil rights and individual liberties. They said they were giving him the benefit of the doubt as "the best we can hope for from this administration," in Biden's words.

"If Judge Souter turns out to be a rigid ideologue and not the moderate he seemed to be {at the Judiciary Committee hearings last month}, then the Senate and the American people will be deceived," said Sen. Herbert H. Kohl (D-Wis.), a committee member.

Kennedy contended that this was too great a risk and said recent experience with Supreme Court nominees suggests that senators "must vote our fears, not our hopes."

Complaining that liberal critics were subjecting Souter to an improper test, Sen. Strom Thurmond (S.C.), ranking Republican on the Judiciary panel, said Souter had a "keen sense of justice, a clear view of the concept of fairness and a deep understanding of the impact his decisions will have on the individuals affected by them."

Reflecting the confusion over Souter's place in the judicial spectrum, liberals who supported him saw a pragmatist who took a broad view of individual rights and the court's role in society, while conservative backers saw a strict constructionist who would spurn judicial activism.

For instance, Biden hailed him for recognizing a fundamental right to privacy and indicating he would use the Bill of Rights to protect minorities, while Sen. Charles E. Grassley (R-Iowa) praised him as "committed to judicial restraint and fidelity to a written Constitution."

While supporting Souter in what he called a "close decision," Biden warned the administration not to "learn the wrong lesson" from the lopsided vote for Souter and conclude that the Senate was relaxing its standards for weighing judicial nominees or drawing the line only at "extremists." A more doctrinaire conservative "could well fall outside the sphere of acceptability," he said.

Staff writer Eleanor Randolph contributed to this report from Concord, N.H.