No administration in Washington has ever taken Libya's leader, Col. Muammar Qaddafi, quite so seriously as this one. For more than a week now, the ruler of a mostly desert nation of some 3 million people has been the center of attention in this superpower capital.
Reagan administration officials are clearly upset that Colonel Qaddafi has been given this kind of publicity. They blame the press for overplaying reports that Qaddafi has organized an assassination plot against President Reagan.
But some of those same officials, including the President himself, had done their part in recent days to dramatize the assassination reports and to portray Qaddafi as one of the most dangerous men in the world.
In the process, they may have frightened Qaddafi, thus at least temporarily deterring him. When it comes to his personal safety and his own nation's security, the erratic Qaddafi is no madman. He has had a history of backing away from a number of confrontations.
But the danger is that the administration may also simultaneously have bolstered and challenged the proud Qaddafi's ego, thus forcing him to seek new ways of striking out against the United States. The publicity given to the Qaddafi case has also put the administration itself on the spot. It is now under pressure to back up its tough words against Qaddafi with action. Furthermore, the publicity may have made more vulnerable the more than 1,000 Americans working and living in Libya.
On Dec. 10 the administration called on US citizens in Libya to return home immediately and announced a ban on US travel to Libya. At the same time Reagan administration officials have urged the press to lower the volume of publicity about Libya.
Who is this man who can command the highest level of attention in a superpower capital for days on end? Monitor reports from overseas capitals indicate that Qaddafi is anything but a madman and that while he may look irrational in Western eyes, he can be a shrewd opponent who still commands enough support in his own country to thwart anyone who would like to topple him.
As Libya watcher G. Henry M. Schuler points out in a forthcoming article for Johns Hopkins University's SAIS Review, Qaddafi does not fit any of the conventional labels - such as ''leftist'' or ''rightist'' - which Western journalists, scholars, and bureaucrats like to apply to the world's leaders. Colonel Qaddafi's strength derives from the Bedouin society from which he came, and it is only in traditional Libyan and Bedouin terms that his resentment of Western influences and his advocacy of Libyan expansionism can fully be understood.
US officials grope for words to describe Colonel Qaddafi: messianic . . . charismatic . . . a visionary. But none of the words seems adequate.
As Mr. Schuler explains it, Colonel Qaddafi's dismissal of organized government is in keeping with the tribal society from which he came. He may have esoteric ideas, but he still lives a Spartan life and periodically returns to a tent in the desert. Qaddafi may appear quixotic in his intention to establish an Islamic state across Saharan Africa, but such a state was a goal of Libyan leaders before the turn of the last century.
According to one of the West's few experts on Libya, John Cooley of ABC news, Qaddafi's ideas derive as well from his long-standing admiration of the late President Gamal Abdel Nasser of Egypt.
In an article earlier this year in the magazine Foreign Policy, Cooley writes that during his youth in southern Libya's Fezzan desert and then at the University of Benghazi and the Libyan military academy, Qaddafi was nurtured on a diet of the Koran and Radio Cairo's ''Voice of the Arabs.'' Qaddafi apparently feels that he is Nasser's heir, holding aloft not only the banner of Islamic fundamentalism but also that of Arab nationalism.
Seen from the West, however, there is a more sinister side to Qaddafi: his support of terrorism as part of his drive to achieve his goals. American officials attribute the deaths of 14 Libyan dissidents in exile to Qaddafi's hit teams. They believe that he was responsible for the shots fired at an American diplomat in Paris recently. They are certain that he planned to kill an American ambassador to Egypt, Hermann F. Eilts, in 1976 or 1977, possibly to disrupt US-Egyptian relations.
Also troubling to the Americans is Qaddafi's Soviet connection. Over the past seven years Colonel Qaddafi has purchased huge quantities of Soviet arms. East German security men help to protect him. There are reports that Qaddafi has sought to obtain nuclear weapons.
A good number of the experts doubt, however, that the colonel is a Soviet stooge and they suspect that in the long run, the Soviets consider the Libyan leader to be unreliable.
The Carter administration tried at first to open a dialogue with Qaddafi. In the case of the suspected assassination plot against Ambassador Eilts, President Carter successfully used quiet diplomacy to warn Qaddafi away, according to Eilts. The theory was that Qaddafi was more likely to become hostile if he was publicly embarrassed, rather than confronted quietly. But a Libyan mob attack on the US Embassy in Tripoli in December 1979 ended any hope of accommodation. The Reagan administration has loudly condemned Qaddafi's backing of terrorism and labelled him an international outlaw. US officials say that Qaddafi is probably convinced that the Reagan administration has been planning to overthrow him and that this might explain reports of a Libyan assassination plot against President Reagan.
But there is evidence that Qaddafi sometimes backs off. He is reported to have cut his support for Philippine rebels and for the Irish Republican Army. His troops are withdrawing from Chad. He was apparently dissuaded from pursuing an assassination plot against Ambassador Eilts. But when he withdraws in one place, he tends to move in another. He has the oil wealth to do so.
''How do you deal with Qaddafi? '' asked one US official. ''A tough line? A soft line? Nobody has quite figured it out yet.''