Since the Iran-contra hearings, bipartisanship in U.S. foreign policy has become the slogan of the day. That goal is not merely desirable; it is essential. But while excessive partisanship has contributed to many recent shipwrecks of American foreign policy, grave damage can also be done when bipartisanship becomes a largely political and tactical maneuver.

In the great days of bipartisan American foreign policy -- from the Truman Doctrine in 1947 till roughly the Vietnam War -- there was substantial agreement on foreign policy objectives. Disagreement concerned means. Exactly the opposite is the case with respect to Central America after the accord between the president and the speaker of the House, Jim Wright. Bitter antagonism over objectives remains. Such consensus as exists relates to tactical moves which are stated in the vaguest terms and are unrelated to realistic schedules or implementing machinery.

The Reagan-Wright accord, which set a deadline of Oct. 10 for bringing a democratic process to Nicaragua, was superseded within days by the Guatemala City peace plan of the heads of government of Central America, who set a different schedule and criteria. In the era of true bipartisanship, executive and legislative compromises supported an agreed national strategy. On Central America they have become substitutes for it.

The predominant (though not exclusive view) in the Reagan administration is that the Sandinista regime in Managua is a threat to the security of its neighbors and ultimately of the United States. Therefore, the administration seeks to achieve not so much specific concessions as a transformation of the Nicaragua government into a pluralistic democracy. Inevitably the anti-Sandinista resistance is for the administration an essential, perhaps a decisive, component of a post-Sandinista political order.

The administration's critics, on the other hand, in large part are opposed to the so-called freedom fighters as a matter of principle. They consider American support for the guerrilla war as insupportable under international law and immoral. Many see the Nicaraguan resistance as the principal obstacle to a settlement. Hence the contras are treated by critics as at best a bargaining chip to be abandoned with greater or lesser good grace.

Neither side reveals its full, or perhaps even its real, agenda. The predominant group in the administration views the Central American peace program as a tactic to oblige Congress to vote the requested amounts for contra aid before adjournment. Many opponents of contra aid seek to use the peace plans to delay such a vote and to turn the domestic debate into a haggle over terms by which the contras can be abandoned.

I have considerable sympathy for the basic analysis of the administration. The fact remains that there has been next to no relationship between the administration's fierce rhetoric and its actions. The contra aid so far requested could not achieve the administration's stated objectives by military means; it would be at best enough for a prolonged stalemate. The administration owes the American public answers to these questions: 1) Are there any terms other than the overthrow of the Nicaraguan political structure for which it would settle? 2) If so, what are they? 3) If the answer is no, what precise effort is required to achieve its goals?

The opponents of contra aid, on the other hand, have refused to accept the reality that without the contras there would not have been any movement on the negotiating front. They must answer the question whether they are prepared to take the responsibility for perpetuating a Marxist-Leninist regime in Managua unconstrained by either security restrictions or human rights provisions. And if they are not, by what means are they willing to insist on what terms?

If these questions are not answered, we will slide into a situation where policy is suspended between a search for victory with insufficient resources and a call for diplomacy drained of incentives.

In an atmosphere where liturgy dominates substance, the one objective on which both supporters and opponents of contra aid agree -- the establishment of pluralistic democracy throughout Central America -- threatens to turn into an evasion of the fundamental issues. The bipartisan Central American Commission (of which I was chairman) -- the last genuine bipartisan effort on the subject -- concluded unanimously in 1984 that Nicaragua would be an overwhelming threat to all its neighbors so long as it continued to rely on thousands of Cuban military and intelligence advisers, was armed by the Soviet Union and retained its Cuban and Soviet-bloc-trained intelligence command and intelligence structure. Turmoil in Central America would ultimately affect the security of the United States 500 miles to the north and of the Panama Canal 300 miles to the south.

One would therefore assume that at a minimum an American peace plan would address specific threats to our security and put forward concrete proposals to reduce or eliminate them, especially as Soviet military assistance and Cuban support have both increased far beyond 1984 levels. But the Reagan-Wright peace plan as well as Guatemala City peace plan made only the vaguest references to Cuban and Soviet-bloc military and intelligence advisers or to the size of Central American armed forces. They focused primarily on the establishment of democratic institutions throughout Central America.

But diplomacy cannot always be equated with social and political engineering. Even with the best will in the world, the Guatemala City peace plan would produce an inherently one-sided negotiation. Managua's goal of ending American support for the contras is unambiguous and easily verifiable. Once carried out, it is irreversible. On the other hand, the achievement of pluralistic democracy permits few objective tests. It is a process that in the West was based on an evolution over centuries and occurred in industrialized societies. Do we really know enough in effect to design institutions for small countries with different histories and economic circumstances? Democratic reform, moreover, can be fairly easily reversed, especially in an agrarian society where there are few indigenous historical roots and where the government believes in a totally different philosophy.

In any event, in Central America good will is likely to be in short supply. Pluralistic democracy is based on the equal status of all political forces; Marxism-Leninism affirms the dominant role of the Communist Party. Western-style democracy is unthinkable without rotation in office. Marxist-Leninist parties insist that as the vanguard of history they cannot permit a reversal once they have seized power. That the dedicated, able and ruthless Sandinista leaders would violate their own deeply held convictions, voluntarily put their own power up for grabs and turn their government into a genuine pluralistic democracy requires a leap of faith of which I am not capable. The Sandinistas may allow some of the trappings of pluralism, as they did shortly after they came to power, but surely with the afterthought of reversing course when objective conditions have changed. And these will have changed as soon as the Nicaraguan resistance is abandoned by the United States. In any event, the various peace plans contain few criteria by which to judge progress, no enforcement machinery and no sanctions.

Ironically, the objective on which the Sandinistas and the Reagan administration may most likely agree -- albeit tacitly -- is to get through the rest of the president's term without having taken irrevocable decisions. The Sandinistas probably calculate that the more time they gain, the less likely will American public opinion support a serious effort to modify either their domestic or their security policies. At the same time the politically and ideologically oriented elements in the Reagan administration -- and they are the majority -- seem more concerned with avoiding the impression that they have accepted the Sandinista regime than to explore security arrangements such as expelling communist-bloc advisers and reducing Central American armed forces.

In these circumstances it would be a contribution to the seriousness of public discourse to recognize that an overall settlement is simply not possible in any time frame relevant to congressional decisions on contra aid. An issue as complex as the democratization of Central America cannot be negotiated by the deadline of Nov. 7 put forth in the Guatemala City agreement. And if by some miracle it were, there would be no way of knowing whether it would be observed. Thus the only overall settlement for Central America achievable quickly would require abandoning long-held positions of the other Central American governments and much that is in America's long-term security and political interest. But that is not the real choice. It is too late in the Reagan administration to resolve fundamental issues of philosophy and of strategy or to adopt the organizational remedies that might end the fitful aspect of much of American foreign policy. But it is emphatically not too late to make sure that issues are dealt with in the calmest possible atmosphere and after a thoughtful debate. The elements of cease-fires and of protecting human rights in the Guatemala City plan deserve careful exploration, but that requires separating them from contra aid.

At this point both sides in the domestic debate can make their best contribution by keeping open the options for the future. The administration must face the fact that it has never sought the means to achieve its objectives. It cannot avoid either scaling down its demands or presenting their real price. If it does so, it will become clear that the present effort -- which is the maximum Congress is likely to allow -- can do no better than to continue a stalemate.

The opponents of administration policy should not take upon themselves the historic responsibility of perpetuating in this hemisphere a Marxist-Leninist regime without any safeguards with respect either to security or to human rights. They should accept the fact that, whatever they think of the Nicaraguan resistance, without them there would never have been even this much movement in the negotiations. Above all, the United States cannot without isolating itself abandon those who have relied on its promise in every decade and on every continent.

Thus, both sides of our domestic debate should have an interest in the following steps:

A. The various peace plans should place much greater emphasis on elements that are concrete and verifiable -- especially the withdrawal of communist-bloc military advisers and intelligence personnel from Nicaragua, the establishment of a severe limit on Soviet-bloc military aid, the creation of a ceiling for armed forces in Central America and an end to U.S. military maneuvers in Honduras.

B. The provisions of the Guatemala City peace plan dealing with democratic institutions should be made much more concrete. It is surely not too much to ask the Sandinistas to accord the same recognition and rights to their armed opposition that President Jose Napoleon Duarte of El Salvador has offered to his guerrilla opponents.

C. Congress should vote contra aid for an 18-month period on the present scale to permit a new administration to set its own policies and to avoid having an issue of fundamental national consequence overwhelmed by the politics of an election year. It cannot keep postponing that decision on the pretext of supporting a peace plan because that will in effect destroy the Nicaraguan resistance.

D. If a verifiable cease-fire should be achieved, contra aid could be transformed into humanitarian assistance (even recognizing the element of hypocrisy in this distinction).

Such a course would reflect true bipartisanship.