NEWS ANALYSIS : Lebanon’s Fragile Balance Tested by Elections : Mideast: Diverse groups reach for power in a nation shattered by war. Syria casts a long shadow over political landscape.

Two months ago, while celebrating a 10-day Islamic holiday known as Ashoura, thousands of Shiite Muslims took to the streets here, radios blaring, horns honking, flags and banners waving from their cars.

Once an impoverished, oppressed minority, the Shiites roared night and day through this city in an aggressive display of their newfound numerical and political strength. Their behavior angered moderate Sunni Muslims and led to scattered fights and an exchange of grenades between the two sects in Beirut and Sidon.

Religious leaders stepped in quickly to defuse the situation. But the brief crisis was a reminder of how fragile the balance is between Lebanon’s diverse communities--two-thirds of Lebanon’s 3.5 million people are Muslim, one-third Christian--and underscored the importance of two elections Lebanon will hold over the next nine months. Both will take place in the shadow of Syria.

Christians plainly see their power diminishing under Syria’s military and political dominance and in the wake of a movement of Shiites into government positions of authority. The leadership of the divided Christian community--former President Amin Gemayel, former Deputy Raymond Edde and right-wing Maj. Gen. Michel Aoun--now lives in France.

Aoun, whose rebellion was crushed by Syria in 1990 with the acquiescence of the United States, says he intends to return to Lebanon to run in November’s presidential election. “I insist on returning through the Beirut International Airport--even if they try to kill me,” he said.

But it’s not at all certain that either the government or Syria will allow him to return.

By law, Lebanon’s president must be a Maronite Christian and can serve only one term. President Elias Hrawi’s term is up in November. But Parliament is considering amending the constitution to allow him to serve longer.

Uncertainty over who the candidates will be and the belief that Syria will decide on Hrawi’s future have made the Lebanese apathetic about the election. “I’d rather go to the beach than vote anyway,” said one university student.

The election for Parliament--which the Christians boycotted in 1992, partly because Syrian soldiers did not redeploy to the eastern Bekaa Valley as agreed--will be next spring or summer. This time, the Christians say, they will run candidates for the 128 parliamentary seats, eight of which were won three years ago by members of the Iranian-backed Hezbollah (Party of God), a radical Shiite group.

Regardless of the electoral outcome, there is a general feeling here that no president or Parliament stands much chance of truly reuniting a country shattered by 15 years of civil war until Syria and Israel make peace and the issue of the Golan Heights is settled.

Once that happens, the reasoning goes, Syria can turn its attention to Lebanon, where Israel controls a “security zone” in the embattled southernmost part of this country. The zone, which Israel patrols with a Lebanese militia made up of Christians and Shiites, has succeeded in stopping infiltration into Israel but not rocket attacks on the Jewish state.

If Lebanon makes peace with Israel--as it surely would, once Syria did--the southern militia would become obsolete and Hezbollah would have no future as a guerrilla organization. Hezbollah, formed in 1982 as a result of Israel’s invasion of Lebanon and eventual siege of Beirut, apparently sees the handwriting and is taking steps to transform itself into a traditional Islamic party.

Besides running candidates for Parliament, Hezbollah has expanded its social services and is building schools and hospitals, advising farmers on agricultural development and running its own commercial television station. Long linked to kidnapings and bombings in Lebanon and abroad, Hezbollah has even put up a sign in English welcoming Western tourists to its stronghold in the Bekaa Valley, site of famous Roman ruins.

Lebanon’s composition is such a sensitive matter that the country has not had a census since 1932.