Hundreds of university students, shouting "Long live popular resistance" and "Down with facism," marched through the streets of La Paz last night as Bolivia continued to slide toward another military coup that, this time, observers say, could precipitate a bloody civil war.

With terrorists bombs exploding nightly here, in Cochabama and in Santa Cruz, the country's three largest cities, with basic foodstuffs already in short supply, with inflation surging toward 40 percent and with the military on emergency alert since last week, Bolivia has serious economic and political difficulties.

The question, in the view of most observers here, is whether the military will overthrow the current caretaker president, Lydia Gueiler, before or after general elections set for June 29, when Bolivians are schedulled to go to the polls for the third time since July 1978.

"Bolivia is a tinderbox waiting to explode," said one Bolivian businessman whose assessments of his country's political health have been right in the past.

"The tragedy is that we have not matured politically since 1978," said the Jose Gramunt de Moragas, a Spanish-born Jesuit priest and journalist who is considered one of Bolivia's most thoughtful political observers.

At the heart of Bolivia's current political instability is its economy, suffering from years of corruption, declining resources, inept planning and massive foreign borrowings that cannot be paid back without severe measures that are politically unacceptable. This is coupled with an inability on the part of Bolivia's civilian and military leaders to agree on what form of government the country should have and who should be president.

The country's generals and colonels express contempt for what Gen. Luis Garcia Meza, the Army commander and leader of those who favor a coup before the elections, recently called "formal democracy."

The country's three major civilian politicians -- leftist Hernan Siles Zuazo, centrist Victor Paz Estenssoro and rightist Hugo Banzer Suarez -- appear to believe in "democracy" only insofar as elections are the only way for them to come to power in a country where the electorate is overwhelmingly poor, largely illiterate in Spanish and susceptible to the simplest forms of political demogoguery.

In last year's elections, none of the three men came close to the 50 percent needed for outright election, but none was willing to throw his support in the Congress to one of the others to ensure a strong president capable of governing. The result was a compromise, caretaker president who was overthrown by the military within three months.

The only factors holding the military back now, according to those familiar with its thinking, are pressure from the United States and, more important, the fear and uncertainty about how Bolivia's farm workers, miners and students would react to another coup.

Last November, when Col. Alberto Natusch Busch overthrew president Walter Guevara Arze, La Paz erupted in spontaneous armed opposition to the occupying military force, leaving more than 200 dead before Natusch was finally forced out after three weeks of strikes and bloodshed in favor of Gueiler.

Some believe that the reaction this time would be even stronger and better organized, leading to a real civil war that the military could not be sure of winning unless it struck quickly and brutally.

Others think, however, that opposition to a coup might decrease if the military were to wait until after the election, which is again expected to be inconclusive. The middle class, which in Bolivia includes even maids in La Paz who have learned Spanish, is believed to be tiring of weak civilian governments unable to cope with the country's deteriorating economy.

Gonzalo Sanchez de Lozada, a centrist deputy and one of the wealthiest mine owners in Bolivia, says he was shocked not long ago by the attitudes of people he talked to at a wedding of a granddaughter of one of his family's cooks.

Many, Sanchez de Lozada said, told him they would vote for the left in the coming election but, because of inflation, expected and even hoped that the military would take over afterward to provide a strong government capable of dealing with the economy.

Such a coup would be a setback for the United States, which supports a continuation of civilian government here and led the international opposition to Natusch last year by withholding recognition of his government and suspending U.S. aid to Bolivia, which now amounts to about $150 million in authorized projects.

Only an all-night efforts by U.S. Ambassador Marvin Weissman Friday night, and the inability of Garcia Meza to win the support of some lower ranking officers, prevented a coup four days ago, sources said. At least eight bombs exploded in La Paz that night in what many observers believe was meant to be a pretext for the planned coup.