When Egyptian President Anwar Sadat was assassinated last fall, Secretary of State Alexander M. Haig Jr. told several top White House aides that "our entire foreign policy depends" on President Reagan attending the funeral.

According to one witness, the aides made it clear they had unanimously concluded Reagan should not go.

Haig quickly shifted his course but retained his emphasis. Later that day, Haig told the aides, "Our entire foreign policy depends" on Reagan staying home. They all looked at the ceiling.

The above anecdote and others that do not reflect credit on Haig come from White House officials who have long favored Haig's resignation. They say his performance that day was characteristic of a clash in styles that made his departure from the Cabinet likely, if not inevitable, this year.

These officials say his inclination to overstatement, the often emotional content of his presentations to the president and a need to put himself at the center and in control of all good advice on foreign policy long ago took its toll on Reagan's aides and more recently on Reagan.

These aides have made the disharmony with Haig clear since the administration began 18 months ago. But, they say, Reagan liked Haig and felt he was an effective, perhaps the most effective, symbol of toughness in American foreign policy.

This year when Haig's deputy, William P. Clark, left the State Department to take over as national security adviser, Haig lost his dominant role in foreign affairs. In the eyes of most senior White House advisers this sealed Haig's fate.

One character trait well known to both Haig friends and detractors is his inability to share authority and power. At the beginning of the Falkland Islands crisis, for example, Haig reportedly wanted to announce that he was going to mediate the dispute. Clark, who had begun asserting his authority, insisted the announcement come from the White House. About that time, Clark issued a memo saying he would have to approve all foreign travel, even that of the secretary of state.

Haig reportedly bristled with resentment. In February, one senior presidential aide said, "Clark is taking over and the question is whether Haig can deal with that emotionally."

Last month this aide said, "Clark is torturing Haig." The aide said Clark was not intentionally trying to cause problems but was attempting to smooth out the differences between various departments, particularly between State and Defense. This is the traditional role of the security adviser, the aide pointed out, adding that Clark apparently had the full backing of Reagan.

At Cabinet or National Security Council meetings, several White House aides say Haig frequently overstepped his turf. At least once, they recall Haig making a presentation that sounded more like the secretary of defense. Defense chief Caspar W. Weinberger remarked that since the defense position had been presented, he would turn to foreign policy.

Reagan had high regard and respect for Haig, according to White House officials, but the president did not feel comfortable in Haig's presence. They say Haig had developed a sycophantic style when he worked for Henry A. Kissinger and Richard M. Nixon. Several aides remember the amazement of Reagan and his advisers when Haig would elevate a simple presentation or argument on a small point to a "big victory" for the president's foreign policy.

"No one else around Ronald Reagan is that way, so it stands out," one adviser said.

Reagan is apparently more comfortable with less intense, less overdrawn advice.

Weinberger once looked at Haig and told a reporter, "Unlike others, I don't believe in flying off the handle."

By most accounts neither does Reagan.

Last month, after the resignation of British Foreign Secretary Lord Carrington, whom Haig had referred to at a private staff meeting as a "duplicitous bastard," one presidential aide passed a piece of paper around the room to Reagan's other top aides at a senior staff meeting. It read, "Duplicitous Bastard Resigns on Principle: A Model."

The senior aides apparently got the point and agreed. Haig was the Reagan administration's Lord Carrington and they hoped there would be a time when Haig, too, would find a principle on which to resign.