Within hours of his confirmation as secretary of state, Alexander Haig put final touches on a document for President Reagan's signature that would enthrone the State Department and its new boss as undisputed foreign policy makers in the Reagan administration.

The document, drafted by Haig and his staffers on the seventh floor in Foggy Bottom, would end 12 years of National Security Council staff dominance over U.S. foreign policy. Specifically, it would establish two working committees to be chaired ordinarily by high State Department officials instead of, as in the past, by the NSC staff director.

The document is doubly significant because of its authorship. Though a presidential directive, it was written not by the new presidential assistant for national security (the NSC staff director), Richard V. Allen, but by Secretary of State Haig.

Haig knows more about how the NSC apparatus works than anyone else in the Reagan administration. Having gained that knowledge during the Nixon years as NSC director Henry Kissinger's top aide, Haig knows what he wants from Reagan: a return to the system of 20 years ago when State Department officials, not White House operatives, ran the committees that control national security communications to the Oval Office.

The rise of Al Haig and the decline of the NSC staff system draws mixed reviews within the Reagan administration. Allen himself utters no dissent. Reflecting the president's wishes, he is helping Haig. Eyebrows lifted when Allen hired Maj. Gen. Robert L. Schweitzer, one of Haig's lieutenants at NATO command in Europe, as a key NSC staffer. That gives Haig a potent ally in the White House.

But Haig as potential Cabinet strongman generates distrust in higher elevation of the Reagan administration. Edwin Meese, the president's closest aide, is said by insiders to consider California Supreme Court Justice William P. Clark as a counterweight to Haig. Clark's selection as deputy secretary of state, despite his lack of foreign policy experience, was based on loyalty to Reagan proven in service as the president's first chief of staff as governor of California.

Even with Clark at State, however, Haig's rise will not be stopped quickly. That was affirmed when Haig sent his unprecedented proposal to the White House reconstituting the NSC not along lines laid down by Allen but fitting his own desires.

Such a concession by Kissinger or Jimmy Carter's NSC director, Zbigniew Brzezinski, would have been unthinkable. The very fact that at this writing the new president has not yet issued his first directive on his desired NSC setup is revealing.

By Dec. 30, 1968, Kissinger had completed the most elaborate study ever made of the NSC structure, which was quickly approved by Richard Nixon in a series of directives that opened his presidency. On Jan. 19, 1977, Brzezinski got Carter's signature on changes he wanted in the NSC system, with Carter's approval going out Jan. 20 as Presidential Directive No. 2.

Allen's failure to perform with the same dispatch demonstrates the sincerity of Reagan's often-expressed dislike for the NSC's staff system of the last dozen years. Reagan simply does not regard the NSC as an invaluable tool of presidential policy making, as did Nixon, Gerald Ford and Carter. Instead, known for his like of uncomplicated bureaucratic structures, Reagan has said he was appalled at infighting between the State Department and the NSC that accompanied the dominance of Kissinger and, to a lesser extent, of Brzezinski.

Reagan's attitude is Haig's launching pad, and few here doubt the secretary of state's capacity to exploit and expand his influence over foreign policy in the months ahead. Yet, besides Meese's caution, stemming from his desire to protect the president, there are skeptics of Reagan's decision within the national security bureaucracy.

They say privately that whatever confusion the old system caused, it guaranteed the Pentagon and the intelligence community equal, sometimes superior access to the Oval Office. To give the State Department so much control over the national security system, they contend, could block that access, by accident or design. If they are correct, national security could suffer. Haig shows no such concern. Yet his ability to deal with the critics and make the new system work will decide just how high will be the rise of Al Haig that began with a presidential directive drafted in the State Department.