Solicitor General Rex E. Lee, who led the Reagan administration's often successful drive to push the Supreme Court in a conservative direction, announced his resignation yesterday after four years as the government's top litigator.

Lee began his tenure under fire from liberals and women's groups who accused him of being too conservative and of politicizing the relatively autonomous office.

But he leaves office under increasingly bitter attack from conservative hard-liners inside and outside the administration who demanded his ouster and insisted that despite his successes he has either ignored or not pushed enough for the administration's views on abortion, school prayer, busing, criminal law and civil rights.

His opponents within the administration often included Assistant Attorney General William Bradford Reynolds, frequently mentioned as a possible successor.

Lee said in an interview yesterday that his long-expected departure was not related to administration infighting.

"I can tell you categorically no one asked me to leave and I was not leaving under any kind of pressure," Lee said. "Four years just seems like a good time to leave, and I literally cannot afford to stay any longer because of my family."

Lee has seven children aged 6 to 22 and will have three in college this fall.

He will leave in June to become a partner in the Washington office of a Chicago law firm, Sidley & Austin. He declined to discuss his salary at the firm, but acknowledged that it would be considerably more than his current $73,600.

Lee shares the administration's views against abortion, busing, racial quotas and judicial activism. He also favors loosening judicially imposed restraints on police and an increasing role for religion in public life, including prayer in the schools.

But the pragmatic, low-key Lee -- a former law clerk to Supreme Court Justice Byron R. White, former head of the Justice Department's civil division and former dean of Brigham Young University Law School -- also insisted on maintaining what he called the solicitor general's traditional "unique relationship" of trust and confidence with the Supreme Court.

That position did not set well with those who wanted stronger advocacy on behalf of an administration that, more than any since the New Deal, has brought its political and social agenda to the court.

Lee "misunderstands both his own role and that of the Supreme Court," James McClellan, head of the conservative Center for Judicial Studies, wrote last fall in a article calling for Lee's ouster.

Lee yesterday called the disagreement largely a tactical dispute. "It's a question of what you can get away with, how far can you push the Supreme Court or move the Supreme Court in the direction you want to go."

Pushing too hard could lead to a fatal loss of credibility before the court, Lee said. "I can breathe fire with the rest of them, but you have to play for the long run."

Even in the short run, he said, the "successes have far outstripped" the losses.

Lee's statistical record of success equals or exceeds that of any recent predecessor, according to longtime court-watchers.

In the last Supreme Court term, the justices agreed to hear about 80 percent of the petitions for review filed by Lee's office. In contrast, they agreed to review about 3 percent of all the 3,878 other petitions filed.

Lee's office won 83 percent of the cases it filed or participated in.

Detractors say that record only shows that he has been playing it safe and asking the court merely for what it would easily give.

Others explain his success rate by noting that his tenure coincided with a period when the court itself was moving in a rightward direction, especially with the replacement of moderate conservative Justice Potter Stewart with the more conservative Sandra Day O'Connor.

But those who often oppose Lee before the court acknowledge his effectiveness.

"Although many conservatives will disagree, I think he has done the conservative cause far more good with his moderate approach," said Alan Morrison, director of the Public Citizen Litigation Group. "He and I continue to disagree on many issues, but he has been quite successful, winning a lot of 5-to-4 [Supreme Courts] decisions that were not easy cases to win.

"The office has done well by its client the administration . Whether they have done well by the United States is another matter."

Paul D. Kamenar, legal director of the conservative Washington Legal Foundation, said Lee generally deserved "good marks" but agreed with other conservatives that Lee was "timid" in pushing the administration's goals.

Lee said his approach resulted in important victories in the last four years that enhanced the power of the executive over Congress and the discretion of executive branch agencies over the judiciary.

Other victories allowed for greater use in trials of illegally seized evidence, for parents to claim state tax deductions for parochial school expenses and for limits on affirmative action plans.

Lee said he felt that, when he pushed too hard for limits on the constitutional right to abortion, the strategy backfired, leading to a ringing reaffirmation by the court of the original 1973 decision. Lee listed that as the biggest loss in his four years.

And when the administration prevailed over the solicitor's office and pushed for tax exemptions for schools that discriminate, it lost overwhelmingly.

Lee said that, if his client wanted everything but he as a lawyer knew that only something less was possible, it would make no sense to go for everything and lose.

"You'll pass up the opportunity" for a partial victory, which is "better than zero," he said, and "later on down the road, at a point in time when it might be possible to achieve the larger objective, you'll then have another precedent against your position that you'll have to overcome. And that just seems elementary."