The Senate Judiciary Committee, in a series of dramatic votes, turned down William Bradford Reynolds' nomination as associate attorney general yesterday. The vote was a stunning rejection of the chief architect of the Reagan administration's civil rights policies.

Several committee members said Reynolds was voted down for the department's number-three position because they believed he had been lax in enforcing laws against discrimination and repeatedly misled the committee in sworn testimony. Some senators called the vote a clear signal to the administration to strengthen its approach to civil rights enforcement.

During a tense morning of parliamentary maneuvering, Republican Sens. Arlen Specter (Pa.) and Charles McC. Mathias Jr. (Md.) joined the panel's eight Democrats in voting 10 to 8 against Reynolds.

The action dealt a rare defeat to a presidential nominee and left White House officials bitter. The nomination can be revived only if the Senate approves an unusual petition to discharge the issue to the floor, which administration officials admitted was unlikely.

Even after the nomination was voted down, leaders of the Senate's Republican majority tried several maneuvers to shift the issue to the Senate floor. At one point committee Chairman Strom Thurmond (R-S.C.) appeared to have succeeded, ordering a roll-call vote while several Democrats were walking out of the hearing room. In the end, however, the Republican-controlled panel could not muster enough support to salvage the nomination.

Although some senators suggested that Reynolds consider resigning as head of the Justice Deartment's Civil Rights Division, he said yesterday that he would remain on the job "to make sure that the progress we have made over the past four years will continue throughout the second term." He said the administration's policies "have been effective in combating unlawful discrimination of every sort."

Specter, accusing Reynolds of selectively ignoring court rulings, said he hoped the nomination hearings "will prove to have enormous beneficial impact on the administration of the civil rights laws."

President Reagan, however, stood his ground on the highly emotional issue. Saying he was "deeply disappointed," Reagan declared in a statement: "That some members of the committee chose to use the confirmation process to conduct an ideological assault on so superbly qualified a candidate was unjust and deeply wrong.

"Let me emphasize that Mr. Reynolds' civil rights views reflect my own. The policies he pursued are the policies of this administration, and they remain our policies as long as I am president."

Attorney General Edwin Meese III also issued a strong statement of support for Reynolds. And White House chief of staff Donald T. Regan blamed the defeat on "a desertion by two Republican senators."

The vote capped four years of bitter controversy in which critics have accused Reynolds of failing to protect minorities, women and the handicapped from bias in housing, employment, education and voting. Reynolds maintained that he has been vilified for his opposition to school busing, hiring quotas and other sweeping bias remedies based on race.

Sen. Patrick J. Leahy (D-Vt.) said Reynolds should step down because a number of senators believe that he misled the committee. "That's why a lot of us opposed him -- we just don't find him credible," Leahy said.

But Sen. Alan K. Simpson (R-Wyo.) said Reynolds had fallen victim to "this ritual of getting pecked to death by ducks." Simpson said no witness could possibly recall the details of hundreds of cases "while some bug-eyed zealots are going through the transcript."

Without naming any civil rights groups, Simpson criticized "the bleary-eyed ones sitting in the back of the room, people who just don't like the philosophy of Brad Reynolds . . . . They haven't got the guts to really say this guy's a dud because he doesn't agree with our interest group."

Frank Parker, an attorney with the Lawyers Committee for Civil Rights Under Law, disputed Simpson's analysis. "Mr. Reynolds defeated himself by the inaccuracies and misrepresentations in his testimony, which were pointed out by the senators," he said. "It was not a matter of people feeding information to the senators; it was the senators themselves."

Ralph G. Neas, director of the Leadership Conference on Civil Rights, said there were several "heroes" on the committee who "made a clear case that Brad Reynolds repeatedly had placed himself above the law and was not candid with the Senate." He called the vote "a big victory for civil rights and for fairness."

Delegates to the NAACP convention in Dallas broke out in wild cheering when news of Reynolds' rejection was announced.

The flurry of action began with the committee's 10-to-8 vote to reject the nomination. Defeat was assured when Sen. Howell Heflin (D-Ala.), who had remained undecided, said he was opposing Reynolds on "the issue of credibility" because the nominee made repeated misstatements.

Thurmond then asked the panel to report out the nomination with no recommendation. "I think the Senate is entitled to vote on this matter," the chairman said. "I think the president is entitled to have the Senate vote. I think the country is entitled to have the Senate vote."

"We're all paid $75,000 a year," Leahy replied. "We have spent tens of thousands of dollars of taxpayers' money on this hearing. We have spent countless hours . . . . That's what we're paid for, to take a stand, not pass the buck."

The panel deadlocked, 9 to 9, with Specter agreeing to send the nomination to the floor and Mathias and Heflin remaining opposed. But then Sen. Paul Laxalt (R-Nev.) surprised even Thurmond by moving to report out the nomination with a negative recommendation, and chaos erupted.

Ranking Democrat Joseph R. Biden Jr. (Del.) abruptly stood up, announced the absence of a quorum and led several of his Democratic colleagues toward the door. But Thurmond went ahead with the vote, which he won 8 to 3. A long shouting match ensued, with Sen. Howard M. Metzenbaum (D-Ohio) accusing Thurmond of having "railroaded" the nomination through.

After a short recess and a bipartisan huddle, Biden apologized to Thurmond for giving the impression that he was trying to thwart the vote by walking out. He said he had simply wanted a recess to obtain proxies for the unexpected third vote.

Thurmond agreed to rerun the final vote on whether to report out the nomination with a negative recommendation. It failed on a 9-to-9 tie.

Reynolds' nomination appeared assured until three weeks ago, when committee members challenged his testimony about two voting rights cases in which he erroneously said he had consulted opponents of election redistricting. Reynolds later apologized for his faulty recollection, but by then opponents had seized on several other statements that appeared to be contradicted by other witnesses or internal Justice Department documents.