The death of two U.S. Marines in military action near Beirut should start the 60-day clock running under the provisions of Section 4(a)1 of the War Powers Resolution. That subsection requires the automatic withdrawal of U.S. armed forces from hostilities or "situations where imminent involvement in hostilities is clearly indicated by the circumstances," unless Congress provides the president with specific approval to continue the involvement.

As one of the principal authors of the 1973 resolution, I urged that the president give notice that he acted under that subsection when the Marines were first sent to Beirut a year ago. This would have been an act of good faith by the president, reassuring the American people that he wanted to share with their elected representatives this awesome exercise of war powers.

Clearly the president a year ago did not regard the exercise as awesome, and he chose to invoke only the reporting requirement of the War Powers Resolution, an important safeguard of the national interest in warmaking, but one that does not require the automatic withdrawal of forces in the absence of congressional approval.

His reluctance at that time was understandable. He did not foresee a prolonged, dangerous presence of U.S. Marines in Lebanon. He expected the evacuation of PLO regulars to enable the Lebanese to take over the management of their own affairs in a matter of weeks.

The departure of Yasser Arafat's troops did not bring tranquillity. After a year the scene is no better. Plainly Lebanese forces cannot control even the capital city.

Our government can blame the Syrians, the Israelis, the Lebanese. There is enough blame to go around. But assessing blame does not relieve the United States of a difficult dilemma. The situation is dangerous and likely to remain so.

The choices available to the United States are painful. None is appealing. The first is to continue the status quo, which means the probability of more casualties and no resolution of the basic problems. In fact, in a stormy situation like the one that now exists, the status quo may be impossible to maintain. More likely, the president will respond to pressures to increase the number of Marines, their firepower and their responsibilities. This step- by-step escalation will inevitably bring memories of our gradual involvement in Vietnam. It will also bring the unpleasant prospect of long- term garrisoning of a country known for its warring religious factions and its inability to have a stable government.

The other alternative is to extricate our forces. This course--in my view, the wisest--is the one least likely to be taken by the president. No president wants the onus of ordering U.S. forces to retire from an incomplete foreign assignment, especially if he ordered them there in the first place. President Reagan does not want to be accused of "losing Lebanon."

He need not bear that onus. The War Powers Resolution gives him the opportunity to bring Congress directly into the decision-making. He can--and should--notify Congress that he is altering the authority under which the Marines are deployed in Lebanon because circumstances there have changed. He will thus instantly make the legislative branch--including the senators who want his job-- share with him the decision on what to do next.

Invoking Section 4(a)1 will give Congress just 60 days in which to come to a decision on whether the Marines stay in Lebanon. The president could extend the 60 days to 90 if he wished. If Congress wants them to stay beyond that time, it will have to say so with legislation. Otherwise, the president will be compelled to withdraw the Marines.

Those in Congress who now urge the president to get the Marines out would be able to do more than sit on the sidelines and plead. They would by necessity take part in a great--and long-needed --national debate and decision over what should be the proper U.S. military role in the Mideast.

I participated closely in the development of the War Powers Resolution as a member of the House Foreign Affairs Committee from the inception of the idea through the override of the presidential veto in 1973. Its basic purpose was to establish for the first time a statutory relationship between the president and Congress in the exercise of the most awesome of all governmental authority, the power to place military forces in situations where hostile action may develop. The hope was that the act would bring the two branches of government into close consultation and coordination without impairing the president's ability to act with dispatch in emergencies.

So far, compliance has been, on balance, good. Lebanon could well be the acid test. Reagan can give the War Powers Resolution new life and utility with the new notification I suggest. By doing so he will set in motion a broad and useful public discussion that will help to establish national consensus and policy.

Even if he elects not to do so, the critics of his policy have another course open. Under Section 5(c) of the War Powers Resolution, Congress, by concurrent resolution, can direct that armed forces be removed from hostilities outside the territory of the United States in the absence of specific statutory authorization. This alternative is available no matter what form of notification the president has given to Congress. It is available even if no notice is given. I am familiar with this provision and its rationale, because I am its principal author.

The Supreme Court in a recent ruling set aside legislative "vetoes" and thus, in the eyes of some people, put a cloud over the constitutionality of this provision. Lawyers within the executive branch have challenged its constitutionality since the beginning. The important fact is that the provision is in the law. It got there through constitutional process. It has not been directly examined by the court. It is one thing for the court to throw out a legislative veto that concerns only relatively minor matters of domestic policy. It is quite another to interfere with the relationship of the president and Congress in the field of war powers. Historically, the court has feared to tread in this area.

In any event, any of the senators or representatives who now plead with the president to withdraw troops from Lebanon will have the opportunity, as soon as Congress reconvenes, to file a concurrent resolution under Section 5(c).

Thus either the president, by changing his war powers citation to Section 4(a)1 or any senator or representative, by introducing a concurrent resolution under Section 5(c), can bring Congress, the people's branch of government, into the vexing decision about what to do about Marines in Lebanon.