It appears that Congress, having hesitantly supported the Nicaraguan contras for nearly four years, is hesitantly withdrawing its support. We think the decision makes sense. The armed resistance has not been effective enough for some Americans or democratic enough for others. This is the right moment to act. Still, the way in which support is withdrawn is important. The United States is entitled to change its mind about a particular operation, but it has a continuing obligation to the democratic cause. If it is not going to support that cause with either indirect or direct military means -- and we do not think it should -- it ought to support it with other means: diplomatic, political and economic.

But let us first address the question of what to do about the 15,000 guerrillas in Nicaragua. Mr. Reagan has retreated to a position that would keep them in place with logistical aid while he sought to bring them into talks with the Sandinistas. But an evolving congressional majority may be ready only to provide refugee assistance to those who quit Nicaragua and to forget about the others. On Sunday the Sandinistas renewed their offer to let contras who surrender leave the country or go home under Red Cross or U.N. supervision. But it is all very mushy. Congress should at least express a decent concern for people who took the chance of relying on American constancy. It is not enough to smear them all with failings of some of the ugly National Guard types among them, or to avert one's gaze.

On Sunday the Sandinistas rejected Mr. Reagan's call for a dialogue with the contras, insisting that they would only talk "to the one who sics the dog on you," the United States. This is the characteristic defiance of a government that believes, not withut reason, that Mr. Reagan means to overthrow it. The Nicaraguan resistance, however, is a legitimate political force. If the Sandinistas expect renewed meetings with Washington, they should be prepared to grant it a role. It would be unthinkable for the United States to ditch the military resistance and the political resistance. Congress must make this plain.

In return for an end to the contra operation, the Sandinistas promised anew on Sunday to start returning to "normalcy." But no one who knows anything about Sandinista Nicaragua will think this pledge has any meaning by itself. The ruling Marxists have used the American-sponsored intervention to tighten their grip; it is absurd to think they will relax beyond a certain point and turn back toward pluralism without an incentive. Political and economic sanctions, wielded necessarily by the United States, constitute an incentive. The Contadora diplomatic process does not need $4 million in symbolic congressional largesse. It needs a convincing affirmation of congressional readiness to wield sanctions if Managua does not play fair.

Congress, in checking a wrong and unworthy military intervention, is on the right track, but it needs to think the issue all the way through.