WHEN CONGRESS adopted its present budget process in 1974, one purpose was to centralize its deliberations, another to reclaim lost power from the executive. The Congressional Budget Office was to be part of both, a congressional analogue and counterweight to the president's Office of Management and Budget.

The budget process has since fallen on hard times. It is much reviled (though not always justly, we believe). CBO, by contrast, has surpassed the highest expectations of its founders. Its first director, Alice Rivlin, who served from 1975 to 1983, set a standard of businesslike, sophisticated and detached analysis that seemed at first to clash with the congressional culture -- and eventually helped to elevate it. Her successor Rudolph Penner, who retired last year, followed in the same tradition.

Together they and the senior members of the House and Senate who gave them room to operate made CBO -- which unlike OMB does not have to follow a particular line -- the most authoritative voice in government on budgetary matters, not merely the numbers but the policy choices. Myths have been dispelled by CBO's good work, the quality of debate has been improved, and Congress has gained important leverage in dealing with the White House.

We sing these praises because now these achievements are in danger of being not destroyed, but smudged. The people who are doing the damage are precisely the ones who in some ways have the most to lose and in the past have recognized the special virtue of CBO and protected it from Congress' own worst tendencies, the party and budgetary leaders of the two houses. Mr. Penner left the agency last March. He had previously given ample notice. His place was taken on an acting basis by Edward Gramlich, formerly his deputy, who was one of perhaps half a dozen candidates in the running to succeed him. When no decision was made by the end of last year, Mr. Gramlich returned to the University of Michigan. A division head is now serving as acting director on a temporary basis.

There is no shortage of qualified people to lead this agency. The apparent reason for the delay is that leaders of the two houses haven't been able to agree on a budget director any better than they can on a budget. This in turn has led predictably to all kinds of speculation as to whose man or woman the next director will be. Nothing can do more harm to this valuable institution than the sense that it is somehow even faintly in the pocket of either house, or either party, or any other group. Its strength depends on its independence. The leaders are now said to be about to make a choice, a year late. They need to do it quickly and cleanly; they should play their familiar little games someplace else.