THE ARGUMENT in favor of holding early elections in El Salvador was always that this would be democratic and thus produce certain political rewards. The attendant risk was always that, in conditions of war and turmoil, the "wrong man" would profit. Well, he did. Roberto d'Aubuisson, a retired officer whose name is synonymous with right-wing terror, organized a party that drew 27 percent of the vote and is now trying to form a five-party coalition of the right to take the action away from the centrist Christian Democrats, who got 41 percent. Second-day doubts are flooding many who, on the first day after the election, were celebrating the fine turnout and the blow it dealt to the left's claims of broad support.

The doubts are not groundless. The prospect of the electoral resurgence of the feudal right is not just ironic but alarming. No such government could conceivably lead El Salvador to a place where most of its people clearly want to go or where the United States could or likely would accompany it. But it is too early, in our view, to throw in the towel. The United States cannot easily turn its back simply because the results may turn out to be displeasing.

What comes now is the play of politics. If the d'Aubuisson party is suspect, its would-be partners are variously less so. The Christian Democrats will be bargaining hard in the next few weeks to detach at least one of them. The Christian Democrats have some good cards. They have strong leaders to keep in the game. Their numbers require that they be consulted in the constituent assembly. They represent reform, the only available bulwark against guerrilla appeals. They alone have a strong Washington connection. Nor does it strike us as likely that the armed forces, which ousted the hard right in 1979, will cooperate in its return in 1982.

To its credit, the Reagan administration is scarcely concealing its intention to use its influence to ensure that the Christian Democrats get their due. President Reagan himself said last night that a retreat from reform "would give us great difficulty." Playing the proconsul has its downside, but at this point it would be self-defeating for the United States to stand on niceties and eschew necessary legitimate steps to strengthen the center. The election added some new complications to American policy. Still, the pluses were plain. The election showed that the people want a political process and it undercut the guerrillas' claim to represent the future.

El Salvador's Catholic bishops had declared that elections could be the beginning of a solution to Salvador's struggle. They had no illusions about either the necessity or the difficulty of a next phase. Nor should Americans.