A CERTAIN AIR of drama had built up over the requirement on the president to certify at the close of a six-month reporting period (it was yesterday) that El Salvador has met the prescribed tests for a continuance of aid. Mr. Reagan did so certify; actually, he bundled the baby off to his secretary of state. His decision is sure to be protested vigorously and in as much detail as he has offered by those in Congress and elsewhere who believe that the aid law's human rights and reform standards have not been met. A messy battle looms.

To a point, it's useful. The certification process has let Congress press the administration to be more forthright on rights and reforms than it otherwise might be. The administration has used congressional opinion as a lever on the Salvadoran government. The government has used administration pressure as pressure of its own.

The utility of all this pressure as a tool of change ends, however, in circumstances like the current ones when it becomes at least conceivable that it will entirely derail American aid. No one contends that the congressional majority that enacted an every-six-months certification requirement had this extreme result in mind. It becomes possible, nonetheless, by virtue of the evident distaste many Americans have developed for staying the course in a small troubled place where the stakes are arguable and where the friendlies are weak and flawed.

We believe it continues to be worth the American while to pursue a better society in El Salvador and to r try to keep the country from going the Nicaraguan or Cuban communist way. The frustrations are not so great--not yet, anyway--that the United States should throw in the towel before its Salvadoran friends do. Having in mind both the staggering difficulty of simultaneously conducting a revolution and a war and the likely nature of the regime that might follow the current one, we feel the president was right to make the certification, as unavoidably political as his judgment is. With the continuing aid he acquires a greater opportunity, and obligation, to steer El Salvador in the direction of justice and peace.

His new report, moreover, does more than fulfill a formal requirement of the law. It contributes to the necessary project of restoring some measure of administration credibility on El Salvador. If anything, the report understates the Salvadoran government's accomplishments in rights and reforms. It does not avert its gaze from the government's lapses. It allows a fair look at the reservations entertained by many administration officials. The report leaves the administration in a better position to counter the often exaggerated and politicized statements of many critics and to try to enlist popular support on a realistic basis.

There remains a further opening for Mr. Reagan: to take advantage of the change at the State Department. Alexander Haig felt that El Salvador was the definitive East-West test case and that the trouble there had to be pursued "to the source." This point of view ran up against the Pentagon's refusal to consider committing American troops, and against a great deal of public skepticism and dismay. Secretary of State George Shultz is in a position to bring official statements down to dimensions more acceptable to others in the government and to a broader section of public opinion.

This doesn't mean the vital foreign communist element of the El Salvador guerrilla campaign can be ignored. It means that Americans should be able to help El Salvador deal with it without being sidetracked by wasting arguments among themselves. of the city in many re