Step right up, folks, and get ready to watch the big fight in the Senate over the nomination of Kenneth Adelman to head up the Arms Control and Disarmament Agency. The promoters would have you believe that you are going to see a Great Debate on arms control policy.

But what you will actually be witnessing is a classic case of the United States government working at its worst: wasting its time, not on the merits of matters but on the constitutional question of who's got the muscle around here. Unless somebody backs away, the only winners will be: (1) that considerable number of Western Europeans opposed to any new deployment of medium-range American nuclear weapons in Europe and already spreading doubts about the Reagan administration's commitment to arms control; and (2) the Soviets, who stand to profit from anything that encourages such doubts -- such as the spectacle of nearly half the U.S. Senate expressing the same doubts.

So shouldn't one side or the other back down? In those mindless melees that break out in hockey games, the tendency is to send the most conspicuous combatants evenhandedly to the penalty box, and never mind who started it. But that's not practical when you are dealing with members of "the world's greatest deliberative body." And in this case, it's clear who started it.

If the presentation of Adelman's candidacy had been planned to offend even senators inclined to give the president the benefit of the doubt, it could not have been more effective. As it happened, it was singularly unplanned. In its haste to tidy up after the unseemly removal of Eugene Rostow from the job, the White House apparently picked Adelman's name, as one insider puts it, "out of the hat." When the word leaked, the announcement was made without due consultation with key members of the Senate.

The breach of form was compounded by Adelman's flustered first appearance before the Senate Foreign Relations Committee. The upshot was that the committee voted 9-to-8 against a favorable recommendation. Then, instead of bottling the nomination up, it passed it along for a floor vote by a comfortable 14-to-3 margin with the advice that it be rejected. At best the White House can only win now by expending political capital it could better use for better purposes.

Whatever the outcome, Ronald Reagan's dedication to arms control will be called loudly into question. The nuts and bolts of what might constitute the right negotiating terms will be held up for inspection to no practical purposes. The Senate can block arms agreements by withholding its consent -- as in SALT II. But it cannot negotiate. Still less can it force the president to do what he -- or the Soviets -- doesn't want to do.

Ah, says the senators, but we can hold the president's feet to the fire by turning the confirmation process into a "message." Perhaps. But if Reagan is like other presidents, what is most likely to push him forward is the sense of doing some grand, historic, politically appealing thing on his own motion. The Senate can only rob him of that incentive by creating the impression that its pressure forced his hand.

There are practical reasons to doubt that a rough, partisan debate over arms control policy -- before there is even the hint of the terms of an agreement to argue about -- will advance the cause the opponents of Adelman profess to be trying to advance. It could well retard it. For what the opponents will be saying, over and over, is that the nomination of Adelman proves Reagan really doesn't care about arms control. Say that often enough, and even those Europeans who now only suspect this will come to believe it -- and act accordingly.

Resistance will grow against the "two-track" allied approach. By its terms, the West Germans and others accepted deployment of U.S. medium-range nuclear weapons by the end of the year only on the understanding that a good-faith U.S. negotiating effort would be made to restrict or eliminate the deployment of such weapons. Since the Soviets already have their medium-range missiles in place, U.S. leverage derives entirely from certainty that the U.S. deployment will go forward in the absence of a Soviet willingness to cut back its forces drastically. Thus anything that feeds Western Europe's reluctance to accept deployment diminishes the Soviet incentive to negotiate.

At this stage, it is not in the nature of political hardball for either the White House or the Senate opposition to back down. That leaves Adelman. He strikes me as an innocent victim of the administration's particular flair for mismanagement. But he is a victim. In a game of inches, he did lose, however narrowly, the crucial committee vote that set the stage for a donnybrook on the floor.

It may not be fair. But the moment is fast approaching, when Adelman may have to consider whether his best service to the administration might not be to withdraw.