By Jim Fish
Special to The Washington Post
Thursday, May 16, 1991; Page A27

BELGRADE, MAY 15 -- Yugoslavia teetered today on the edge of its most serious leadership crisis since the death of Marshal Tito a decade ago as the collective presidency of this ethnically hybird country stood deadlocked over the transfer of power from a Serb to a Croat as head of state.

The annual rotation of the chairmanship of the eight-member presidency is normally a mere formality among the six republics and two provinces that make up the country, but today's scheduled installation of Stipe Mesic, Croatia's representative on the presidency and its current deputy chairman, was blocked by Serbia. With no explanation, outgoing chairman Borisav Jovic, a Serb, led the vote against Mesic, leaving him one vote short of the required majority.

The meeting of the presidency broke up in discord, and at midnight -- when the one-year term of the chairman and his deputy expired -- Yugoslavia was technically leaderless. Hopes for a compromise hinged on resumption of the presidency session Thursday morning, but few analysts here were optimistic.

The blocking of Mesic, which is without precedent here, drove another wedge between the hostile republics of Serbia and Croatia -- Yugoslavia's two largest and most populous -- and further undermined efforts to reconcile their bitter dispute over the future of the country.

An official at the Italian Ministry of Foreign Affairs said the blocking of the leadership transfer could "provoke an institutional vacuum with negative consequences for the whole Yugoslav political framework," according to the Italian news agency ANSA.

This latest crisis has its roots in the election victory in Croatia a year ago of the staunchly nationalist Croatian Democratic Union (CDU). Since then, Franjo Tudjman, Croatia's president and CDU leader, has pressed hard for the transformation of the postwar Yugoslav federation into a looser alliance of independent republics, while Serbia has strongly opposed any decentralization of power.

Ethnic Serbs living in Croatia fear a reincarnation of the pro-Nazi Independent State of Croatia during World War II in which thousands of Serbs and others died in Croatian concentration camps and pogroms.

Croatia's Serbs have had the tacit backing of Serbia in their resistance to the Croatian government in Zagreb. After Serbia's hard-line Marxist President Slobodan Milosevic was reelected with a handsome majority in December elections, Serbian resistance in Croatia became a full-scale insurrection.

More than 20 people have been killed in clashes in Croatia in recent weeks -- mostly Croatian police ambushed by Serbian separatists fighting for union of their region, Krajina, with Serbia.

The Yugoslav army last week was authorized by the presidency to separate the opposing forces in Croatia, but army units have stopped short of trying to disarm either side.

The blocking of the Mesic inauguration was denounced by Croatia and its allies as a clear Serbian push for supreme power, with the army -- led by a largely Serbian officer corps -- ready to support such a move.

Milan Kucan, the president of the Yugoslav republic of Slovenia, described the presidency confrontation as "a disguised coup d'etat." Tudjman, referring to Serbia, said "today it is clear to the world who is responsible for this crisis."

Tudjman vowed that Croatia will take further steps to leave the federation if Serbia continues to block Mesic. However, that almost certainly would spark even more ferocious resistance among Croatia's 600,000 Serbs. That, and the vacuum at the top of the civilian leadership, in turn could push the army toward greater intervention, possibly even military rule, analysts said.

Even if Serbia drops its objections to a Croatian president, there is no compromise in sight between the two republics. Extremists on both sides are arming themselves in preparation for civil war. Croatia has an estimated 40,000 men under arms; Serbia, with a greater population, has a large pool of unemployed youths anxious to sign up with the "volunteer brigades" that have pledged to fight alongside their brethren in Croatia.

If the presidency disintegrates, there will be no national body with the authority to negotiate a way out of either civil war or military intervention. Foreign intervention, perhaps by the European Community or the United Nations, is possible, but the likelihood of such action is uncertain.