Must we now suffer through yet one more overblown struggle for power in the making of foreign policy? Will Muskie versus Brzezinski be the equal of Brzezinski versus Vance or come close to matching Henry Kissinger's classic knockout of William Rogers in the early seconds of the first round?

Among those for whom "power" is the only game in this town, the answer has to be: yes. The fight promoters are already at work. Even before Sen. Muskie had been named as Cyrus Vance's replacement as secretary of state, Brzezinski -- presidential assistant for national security affairs -- had been proclaimed the winner, his influence clearly on the rise. At the White House weighing-in ceremonies for Muskie, the first question put to the new challenger was whether he thought he would be "No. 1 spokesman on foreign policy."

Muskie's answer that "the president has left no doubt in my mind" hardly settles the matter. When Vance pushed his differences with Brzezinski to the point of confrontation in mid-1978, President Carter pronounced the secretary to be the principal official voice of American foreign policy (apart from the president) -- and the subsequent sense of order and coherence lasted roughtly six months.

And neither did Brzezinski's over-the-shoulder answer settle anything, when he was asked whether he had ever had an argument with Cy Vance. "Never," he replied, right out there in public, which says a lot more about the Brzezinski sense of humor than it does about the true state of the strained, sometimes close-to-explosive Vance-Brzezinski relationship.

So you have to look beyond these first impressions for some hints as to how things are likely to work out between Brzezinski and Muskie, and also beyond what is obvious in their personalities, talents and temper. It is conventional wisdom that Muskie is tough and touchy, short-tempered and new to the policy-making game; that Brzezinski is almost irrepressible in his reach for the limelight, skilled in the arts of bureaucratic infighting, with close and intimate access to the president. It is not hard, in short, to set them up for a fight.

But, frankly, for the foreseeable future -- which cannot in practical terms be reckoned beyond next Jan. 20 -- I don't think that fight is going to come off.

Rather, my hunch is that while the installation of the senator at State won't resolve every policy dispute in his favor or put an end to the struggle for influence with the president, it will -- at least as a matter of public perception -- reestablish the State Department as the principal exponents, along with the president, of the U.S. position on issues of foreign policy.

This is likely not because Muskie is necessarily smarter or tougher than Cy Vance, or more respected by the president -- or more attuned to the thinking of Brzezinski. On the contrary, a case can be made, on admittedly slim evidence, that his approach on a lot of issues is closer to that of Vance. He has pushed hard for arms controls, resisted increased defense spending. If he came late to opposition to the Vietnam War, by his own admission, that experience also apparently left him all the more skeptical about the effective application of military force.

So what will be different? Nothing much in the president's approach, if past performance is any guide. There is no reason to expect radical change in his deep, down-to-the-last-nit involvement in foreign policy-making, other than the prospect of a more active campaign role now that he has freed himself from his self-imposed confinement to the White House. Nor is there likely to be any less tendency on the part of the White House, leaving Brzezinski aside, to impose domestic political imperatives upon the making of foreign policy.

What will be different, however, is the obvious difference between Muskie and Vance -- one a seasoned, professional politician on a national scale, the other a corporate lawyer and government in-and-outer with no electoral experience. What this means, for one thing, is that the White House politicos will be dealing with a secretary of state whose sense of the politics of things is no less sharp -- and probably a good deal sharper -- than theirs.

But Muskie's political expertise is only a part, and almost certainly the least important part, of the difference between him and Vance. Much more important, in the view of those who have dealt with both men, is the way in which his politician's instincts will influence Muskie's view of the importance of the appearance of who's in charge -- who's really speaking for the president.

Vance, as one aide puts it, cared deeply about what was thought of him personally: of his integrity and decency and grasp of affairs. He cared for issues. But he had no taste for headline-hunting, glory-seeking, credit-taking and all the rest. Politicians, on the other hand, tend to worry quite a bit about the public perception of their own importance. Public perceptions, after all, are what getting elected is all about, and while this rule has not always worked in Muskie's favor, getting elected is something he knows quite a lot about.

Power is something else the senator is familiar with. And while it might not be in his nature to abuse it, it is demonstrably in his nature to speak his mind -- and to speak in terms of harsh realities.

Those same instincts will influence his performance as secretary of state. And while they will no doubt be tempered by a sense of order and responsibility, they cannot help but be reinforced to some degree by what may be the best reason of all to predict for him a predominant role in the making and the propounding of American foreign policy. It cannot heave escaped his notice that the president could ill afford to lose, in the course of one campaign for reelection, two secretaries of state.