President Reagan now faces in Lebanon the greatest crisis of his presidency. In the short run, he appears to lean toward reinforcing the American commitment in Lebanon following the Beirut bombings that took the lives of at least 135 United States marines and 27 French soldiers.
But most analysts predict that in the long run, strong pressure from the public and Congress will force the President to focus more intensively than ever before on a negotiated way out of the Lebanon crisis. This will require a skillful use of both force and diplomacy.
Reagan's response to the crisis could determine whether he is reelected or not, if he decides to run for a second term.
A recent poll showed that half of all Americans oppose the involvement of US marines in Lebanon and that even more Americans fear that the nation will be drawn into a major war there. Earlier polls have indicated that Mr. Reagan was not making a great enough effort to reach arms control agreements with the Soviet Union. A peaceful outcome in Lebanon could do much to overcome public fears about the President's approach to the issue of war and peace.
In his initial public reaction Sunday to the attack on the marines, Reagan denounced the ''bestial nature'' of the bombings and declared that they cannot drive the Americans out of Lebanon. He reasserted that Lebanon was a nation of ''vital and strategic'' importance to the US. Defense Secretary Caspar W. Weinberger said the US was looking for ways to reduce the marines' vulnerability , including a possible new location for them.
From Congress, there was little sentiment in favor of an immediate pullout of the marines. Indeed, some members favored a short-term reinforcement of the US contingent in order to protect the marines who are still there. But Sen. Sam Nunn (D) of Georgia, an influential member of the Senate Armed Services Committee, seemed to express widespread sentiment when he said the marines' mission needed to be more precisely defined.
Appearing Sunday on the NBC television program ''Meet the Press,'' Senator Nunn proposed that the marines be reinforced in the short run to protect the remaining force. But in the long run, he said, United Nations peacekeeping forces ought to replace the marines. He asserted that the current American policy of trying to clear all foreign forces out of Lebanon was ''mission impossible.''