Objections to Libya's anti-American leader Muammar Qaddafi and a dispute over the fate of about 75,000 nomads in northwest Africa could result in the dissolution, by the end of the year, of the organization representing 400 million Africans.

For the first time in its 19-year history, the Organization of African Unity was unable to hold its annual summit meeting last weekend in Tripoli, Libya, because it could not muster a two-thirds quorum of its 51 members.

A five-nation committee was set up to try to persuade the approximately 20 nations that boycotted the summit to attend one later in the year in Tripoli. Blaming the United States for the boycott, Qaddafi has threatened to hold a "rump" summit and form a breakaway African movement if this second attempt fails to achieve a quorum.

That would create Africa's worst political crisis, dividing the continent into two camps, roughly along the lines of "radical," left-leaning nations and "conservative" ones closer to the West.

The continent thus would lose one of the cherished aims proclaimed when the OAU was established in 1963 -- limiting outside pressure, especially from the big powers.

Qaddafi originally had proposed going ahead with the summit without a quorum but apparently was dissuaded by some of the more moderate leaders in Tripoli, including Julius Nyerere of Tanzania and Kenneth Kaunda of Zambia.

The ostensible reason for the boycott was the recognition by the OAU of the Sahara Arab Democratic Republic, whose Polisario Front guerrillas are fighting Morocco for control of the desolate former Spanish colony of Western Sahara. More than a dozen former French African colonies and a handful of Arab nations joined Morocco in refusing to attend as long as the Polisario group was regarded as a member.

However, Qaddafi was probably as much a reason for the failure of the conference. By holding the summit he automatically would have become the recognized representative of Africa in world forums for the next year. As the bete noire of the United States in the Arab world for his alleged support of terrorism, Qaddafi also had a number of enemies among African leaders, who accused him of meddling in their affairs and, in some cases, trying to overthrow them.

Some African heads of state recall their embarrassment when former Ugandan dictator Idi Amin carried the mantle of African leadership in 1975-76 after holding the summit in Kampala, and they feared a repeat performance under Qaddafi.

Since the OAU had confirmed the Tripoli conference site by consensus last year, however, it is unlikely that a boycott on those grounds alone could have deprived Qaddafi of a quorum.

Enter the issue of Western Sahara, about half the size of Texas with a mainly nomadic population considerably smaller than that of Alexandria, Va. Most of the area is within the Sahara Desert, under which there is one known resource -- reserves of phosphate, a major ingredient in fertilizer -- estimated at 1.7 billion tons.

Morocco, a key Arab ally of the United States, and the Polisario Front, supported by Algeria and lately Libya, have been fighting a war over the territory ever since Spain pulled out in 1975.

Morocco, which has committed about the same number of troops as there are civilians in Western Sahara, controls a narrow coastal strip including the capital, El Aaiun. Polisario occupies the eastern area along the Algerian and Mauritanian borders and has proclaimed its own capital. The no man's land in between belongs to whichever troops happen to be on patrol on a given day.

The OAU's outgoing secretary general, Edem Kodjo, precipitated the crisis at the organization's meeting of foreign ministers in February when he proclaimed the SADR a member because a majority of OAU nations had recognized it. Morocco and its allies walked out of the meeting, saying that only a two-thirds majority at a summit meeting could take such a decision.

Ever since then, OAU meetings have been paralyzed, and the conservatives have been able to combine that issue with opposition to Libya as a summit site to block the meeting.

Qaddafi has charged that the United States, which ordered its citizens to leave Libya last December, sabotaged the summit, but he has presented no evidence.

It is possible that the United States played a role in the absence from the meeting of Kenyan President Daniel arap Moi, the outgoing chairman of the OAU. Moi's presence was essential to hand over the mantle of leadership to Qaddafi.

U.S. ambassador William Harrop met with Moi last Tuesday, and much of the session dealt with the OAU. Two days later Moi announced he would only attend the conference if there were a quorum. That almost guaranteed that the summit would fall short of the required number.

It was questionable, however, whether Moi would have attended anyway, because he survived a coup attempt just four days before Thursday's scheduled opening of the summit.

The OAU has survived worse crises, and some analysts think the organization will come through the current one, perhaps by shelving Polisario's admission and shifting the summit to its headquarters in Addis Ababa, Ethiopia, even at the risk of alienating Qaddafi.

The OAU has failed to resolve many of Africa's thorniest problems, including civil wars in Nigeria, Angola and Chad, two major wars between Ethiopia and Somalia and numerous battles over borders. These and other failures have tended to make a mockery of the name Organization of African Unity. "The only relevant word in the title," a cynic said, "is the word 'of.' "

Nevertheless, the OAU has given impetus to the formation of regional groupings for cooperation in trade, transportation and communications.

Its main success has been to provide a platform for the struggle to end colonialism on the continent and to encourage opposition to South Africa's white-dominated government.

In their first generation of independence, there is probably no more reason for Africans -- separated by huge distances, many languages and widely varied cultures -- to be unified than Europe was at the birth of nationalism in the 19th century.