PERHAPS THE guerrilla FMLN on its own will resolve the American debate over the terms on which to aid the government of El Salvador. By moving into a new offensive or by taking negotiating positions so extreme as to be repudiated by that government's harshest American critics, as is already happening, the FMLN may leave Congress no choice but to renew aid on old terms.

This would be a misfortune. An untrammeled flow of military aid would undercut both lagging Salvadoran efforts to bring the murderers of the Jesuits to justice and determined American efforts to punish the Salvadoran armed forces for human rights crimes. It would keep the war going in a spurious quest for unilateral advantage. More immediately, it would choke off prospects to use aid as a lever to end the war.

It is already accepted in Congress and the administration -- less so, as you would expect, in El Salvador -- that some aid is going to be cut to penalize the army for its Jesuit cover-up. The House has already acted. At this late point, there is no other way left to convey American disapproval of such horrors.

That leaves open the question of how to handle the rest of the aid. Critics are no more eager than makers and supporters of policy simply to hand El Salvador over to Marxist guerrillas who are as bloody-handed and undemocratic as the worst government-side thugs. But their approaches are different. Critics focus first on aid conditions meant to influence the behavior of Salvadoran armed forces. The Bush administration and Salvador's civilian government are composing a focus on the FMLN. They propose to cut military aid in return for FMLN acceptance of a cease-fire supervised by the United Nations and the Organization of American States.

As the Senate composes its views on this issue, the cease-fire idea deserves favor. Simply ending or reducing aid, after all, leaves El Salvador on fire and invites the guerrillas to stonewall in negotiations. But giving aid in conditions of a proper cease-fire ends the war. The FMLN complains that a cease-fire reached before the critical issue of military reform is addressed invites the government to stonewall. But a cease-fire could calm passions and produce an atmosphere infinitely better suited than war in which to pursue military reform, human rights and elections. The guerrillas' legal political arm ran as a party and got barely 3 percent of the vote in the last elections. But the FMLN's reluctance to enter peaceful, internationally supervised political competition surely cannot be accepted as a reason to continue the killing.