Critics say the administration is bent on a military solution in El Salvador. But this is misleading, too much a liberal bleat. The administration fears that the left's proposed political solution would amount to a grab for unearned power. It thinks American openness to it would undercut the American-Salvadoran proposal--for the left to put down its arms and join government-run elections--and panic our friends through Central America.

Some critics may feel that by political pressure they can force President Reagan to adopt a policy that he believes would end up installing in El Salvador a regime hostile to American interests--another Cuba or, with qualifications, another Nicaragua. I don't think this is likely, given the politics of the issue--most Democrats, however restless, are leery of being charged with "losing" El Salvador-- and given Reagan's nature.

If he is to alter course, he must be offered some assurance that a broader negotiation would produce a better result than he can expect from sticking to his and the Salvadoran government's current policy of pressing the war and offering only the narrow talks on government-run elections. Americans as a whole deserve such reassurance from those who urge another line. It is not enough merely to say that things are going badly.

Reagan and his chief aides have been rigid on negotiations. But their suspicions are not spun of air. There is plenty of testimony to the guerrillas' commitment to revolution and armed struggle and to the hostile intent of their sponsors in Managua, Havana and Moscow. The precedents, where relevant, are not comforting. The hard question has to be addressed: why should the guerrillas accept the smaller share of power they could hope to get by elections when they may win it all by arms or American default over a period of time?

A tough-minded answer comes from Robert Leiken of the Carnegie Endowment for International Peace, who has talked with Salvadoran guerrilla leaders. Writing in the June issue of Worldview magazine, he suggests:

That the guerrilla front respects the difficulties of winning the war, not least the dangers of drawing the United States more deeply in. That perhaps two-thirds of the guerrillas, though on the left, stand at some political distance from the Soviet Union. That the front's pitiless attacks on the economy have cost it popular support and force it now to cater to the people's craving for peace. That the front realizes a government produced by a military victory would have serious economic and political problems, especially with the United States.

All this helps explain why, in Leiken's analysis, the guerrilla front has "progressively softened its negotiating position even as it has gained ground militarily." Though it rejected dialogue with the reformist junta that took power in 1979, it calls now for unconditional negotiations with the right-of-center government currently in power.

In this light, it is worth looking at the way in which the guerrillas, along with their civilian partners, freshened their call for negotiations last week:

The combined left challenged the president's special envoy, Sen. Richard Stone, to a "direct dialogue." It asked the Salvadoran government to say what parties or elements of substance its newly appointed "peace commission" actually speaks for. It urged the would-be mediators of the Contadora group--Colombia, Mexico, Panama, Venezuela--to get further into the act.

The left's position has plenty of hooks and curves--the snide demand that a dialogue with Washington take place "in the presence of witnesses from the U.S. Congress." But it also has a core of apparent reasonableness which, I think, the administration and the Salvadoran government have increasing reason to address in a manner appearing no less reasonable.

No one can say with confidence that the broader negotiation would satisfy the United States' legitimate security and political interests, plus Reagan's political requirement not to "lose" El Salvador. But one can say with confidence that the narrower negotiation, requiring the left to disarm to engage in elections run under the undisciplined Salvadoran security forces, will not get off the ground. Meanwhile, the war goes on and, though the guerrillas may doubt it, most Americans believe there are real limits to what further military steps we can take.

The administration needs to be open to a wider inquiry into the prospects of a negotiation that would actually end the war. Americans and Latins who favor such a negotiation, including the guerrillas, should think of concrete ways to convince skeptics. El Salvador, do not forget, is a country dying.