White House chief of staff Howard H. Baker Jr., viewed as the solution to a leadership crisis for President Reagan when he went to work for him last February, has instead been seen recently as part of the problem by those who deal regularly with the administration.

After nearly nine months in a job that had been uniquely influential in the Reagan presidency, Baker is beleaguered by criticism from conservatives, who accuse him of trying to scuttle the Reagan agenda, and friends on Capitol Hill, who complain of his failing to save the president from such mistakes as the nomination of Judge Douglas H. Ginsburg to the Supreme Court.

Baker became depressed last week, according to associates, about his lack of effectiveness in influencing the president. They said he criticized himself for not standing up more forcefully to Attorney General Edwin Meese III and sparing Reagan the political embarrassment of the Ginsburg affair.

"Ginsburg was a litmus test of Howard's influence, and he flunked it," one Baker friend said.

Baker had made clear to others in the White House, even before Ginsburg admitted to having smoked marijuana, that he thought Ginsburg was unsuitable for the Supreme Court and had almost no chance for confirmation by the Senate. Baker was bluntly disparaging of Ginsburg and his views on civil rights in these private conversations, according to knowledgeable sources.

Baker also argued long and loudly against Ginsburg in a meeting with Meese and their aides at the Justice Department, according to sources. But they said that Baker did not put this view directly to the president at the White House the next day, when Reagan chose Ginsburg at the urging of Meese.

"Neither Jim Baker nor Donald Regan would ever have allowed Meese to be in the room at the decisional meeting, urging the president to make a snap decision," said one Republican who knows both former Reagan chiefs of staff, Treasury Secretary James A. Baker III and Donald T. Regan.

"They would have postponed a decision and told the president privately later that Ginsburg had no chance, which is what Howard believed," this Republican said. "But Howard is a Tennessee gentleman who believes in the politics of inclusion. He will not freeze people out, even in the best interests of the president."

This has enabled Meese and other conservatives to increase their involvement in White House decision-making. "The right-wingers don't like Howard," said a Republican senator who is supportive of Baker. "But they've taken advantage of his sense of absolute fairness."

As Reagan nears the end of his presidency, facing crucial challenges of an unresolved budget deficit and summitry with Soviet leader Mikhail Gorbachev on nuclear arms reductions, the struggle between "conservatives" and "pragmatists" inside the administration over the legacy of the Reagan presidency has erupted with new and powerful force. While the president has had to maintain his equilibrium after being shaken by Nancy Reagan's cancer surgery, the death of her mother, the stock market dive and Senate rejection of Supreme Court nominee Robert H. Bork, chief of staff Baker became the focus of this renewed battle for the heart and mind of the president.

"He's so genuine and able a man, and the jungle fighting is awesome for him," said Sen. Alan K. Simpson (R-Wyo.), a Baker supporter. "He says, 'I go to bed at night, and I get up in the morning, and I go in there {to the White House} and hide.' "

Baker said in an interview Thursday that Reagan had done "extraordinarily well" with the pressures of the past month but confessed he had been worried about how the president would deal with them.

"I was apprehensive about that, and I was prepared to adjust his schedule to accommodate him," Baker said. "But I have never done so. His concentration did not flag, his workload was not lightened, he showed the usual amount of what I would expect in terms of anxiety but never missed a stride."

However, some said that Baker missed a stride or two. One visitor to the White House during the critical period after Black Monday on Wall Street, who wanted to discuss economic policy with presidential aides, was told that the chief of staff, an accomplished amateur photographer, was taking pictures in the Rose Garden.

Some of Baker's friends also said that Baker has made no secret of being worn down by pressures and attacks from right-wingers and has sometimes spent less time at the White House than his predecessors. They added that Baker is a family man devoted to his wife, Joy, who has had a number of ailments since undergoing cancer surgery five years ago.

A Capitol Hill source who expressed admiration for Baker's willingness to set aside presidential ambitions and enter the White House "during this most difficult period" observed that he often delegates important matters to White House deputy chief of staff Kenneth M. Duberstein.

In late September, for example, Baker departed for his Tennessee family home on a Thursday, leaving Duberstein to round up Republican members of Congress who were trying to persuade the president to sign a politically important deficit-reduction bill. Reagan yielded to their entreaties but also denounced the legislation he was signing, sending what one of the legislators called "exactly the wrong signal to Wall Street."

It is also Duberstein, one of the few veterans among senior aides from the Reagan first term, who has become the principal liaison between the White House staff and Nancy Reagan. She was instrumental in forcing the resignation of Baker's predecessor, Regan, after he became highly unpopular and ineffective on Capitol Hill, where the Iran-contra investigation was threatening to damage the administration seriously.

Baker was in Florida when the president called to offer him the job, so Reagan talked to Baker's wife, who told him that Baker had taken his grandchildren to the zoo. "Well," the president told her, "tell him I need him because we've got a zoo up here."

Baker arrived at the White House, telling associates of his desire to bring Reagan safely "home to port" at the end of his term. He then enjoyed enormous goodwill as a successful conciliator on Capitol Hill.

But Baker also was resented by some conservatives who considered themselves keepers of the flame of the "Reagan revolution." A Baker aide said the conservative view of him became "locked in" during 1978 when Baker, as Senate minority leader, played a key role in the Senate's approval of the Panama Canal treaties that Reagan strongly opposed.

During Reagan's first term, then-chief of staff James Baker and deputy chief of staff Michael K. Deaver had largely succeeded in isolating from decision-making those whom they considered conservative ideologues. One ally of James Baker said at the time that "Reagan supplies his own ideology. . . we appeal to his pragmatic desire for success."

But one of his friends said that Howard Baker, coming into the White House when ideological passions were relatively subdued, suffered from "a mistaken view that he could appease the right in the White House as he had to a large degree in the Senate."

Gary Bauer, a conservative Education Department official whom Donald Regan had brought in as domestic affairs adviser, was assured of a continuing major role. Meese inserted one of this long-time aides, T. Kenneth Cribb, as assistant to the president for domestic policy. James C. Miller III, whom Baker quickly came to regard as an irritant, remains budget director.

"There is an incorrect assumption that Ronald Reagan is a blank slate," said a Republican who has dealt with him for many years. "There really is sort of a rock in the middle of that with basic views. You can fiddle around with them on the margins, but you can't change the views. . . . What you have to learn to do is present your solution within the framework of his philosophy."

James Baker had been an experienced staff man and had the invaluable assistance of Deaver, the aide closest to the president and his wife. Regan, who succeeded Baker, lacked political skills but was close to Reagan, although not to Nancy Reagan, and willing to use the power and proximity of his position to have the last word with the president.

"When Howard Baker came to the White House, he was walking into a role that he had never performed before," an aide said. "It may be the best staff job in the country, but it is a staff job, one step removed from the decision-making job. Until then, every time he was making the decision. It was a whole new environment for him."

In the Senate, Baker had operated by consensus. As Sen. Bob Packwood (R-Ore.) put it last week, "Howard is always looking for a way to compromise things {among} people on occasion with irreconcilable philosophies, among people who want to punch each other in the nose . . . . His philosophy has always been that if there are a dozen disasters coming down the track, you may as well lie down, because 11 of them will derail before they get there and the other will roll over you anyhow."

White House communications director Tom Griscom, who is close to Baker, added that it is "not his nature to be confrontational . . . and if people had seen a different Howard Baker they wouldn't have believed it. His stock in trade is to make the trains run on time."

But a number of Baker's friends, on Capitol Hill and in the administration, have concluded this approach, while successful in the Senate, has proved disastrous in the Reagan White House.

The first sign of this occurred early in the Baker tenure when he recommended to Reagan that he sign an $87.5 billion highway and mass transit bill that the president had decried as a pork-barrel budget-buster. Baker believed it would be difficult to sustain a presidential veto since a number of conservative Republicans from western states who usually supported the administration had backed the bill because it eliminated the 55-mph speed limit.

However, Reagan vetoed the bill anyway and decided to make an appearance on Capitol Hill to sustain it. "This was a disastrous move," said a Republican who opposed it, and James Baker would have found a way to head it off. "Howard didn't really try. He was reluctant to play the 'Nancy card' or any card. His view was that he had given his recommendation, and the president could do what he wanted."

A friend of Howard Baker said that his reluctance to push his opinion more strongly reflects his view both of his role and that of the president's. "He is a little awestruck by the presidency" despite a long relationship with Reagan, a friend said. "This makes it difficult for him to weigh in hard."

Staff writers David Hoffman and David S. Broder contributed to this report.