LA PAZ, BOLIVIA, NOV. 20 -- Congress voted today to impeach eight Supreme Court justices, and opposition politicians prepared criminal charges against the president for extraditing a drug kingpin to the United States, threatening Bolivia's fragile political and economic stability.

In a raucous 14-hour session ending at 6 a.m., the governing coalition rammed through the impeachment motion, charging eight of the 15 top judges with "willfully betraying the public trust." The justices were suspended from the court and prohibited from leaving the country.

The case now goes to the Senate for trial, where the government is seeking alliances that would give it the two-thirds majority necessary to fire the judges.

In the same session, opposition Congressman Edwin Rodriguez announced he was initiating impeachment proceedings against President Jaime Paz Zamora for "violating the constitution" by turning Col. Luis Arce Gomez, a suspected drug kingpin, over to the U.S. authorities earlier this year in the absence of an extradition treaty.

Today's actions in the Congress are the latest salvoes in an 18-month-old battle in which the governing coalition and the main opposition party have sought to destroy each other's political legitimacy.

Politicians across the spectrum said the crisis threatened the nation's democracy, which was restored in 1982 after decades of military rule.

"The entire international community views this struggle as a major blow to democracy in Bolivia," said a Western diplomat who has consulted extensively with his colleagues. "We all feel this is very serious."

Bolivia, a landlocked nation of 7 million, is the largest recipient of U.S. aid in South America. In fiscal 1990 it received $90.8 million in economic assistance and $49.4 million in military and anti-narcotics aid. Bolivia is the world's second-leading producer of coca leaf and cocaine.

"This has turned into a snowball that has grown so big it is no longer possible to say who is right and who is wrong," said Jorge Lazarte, a political scientist with the National University. "It is an unprecedented institutional crisis, brought on by the institutions themselves, that will have more severe results than either side can see at this time."

Because of its long history of coups, rumors are sweeping the capital of imminent military takeover, secret pacts between politicians and officers and the resignation of Paz Zamora.

"I would say at this point that any of those scenarios are highly unlikely, but in Bolivia you can never discount anything," said a Western diplomat. "The truth is, the military does not feel it can handle the mess either at this time."

Beginning in 1985, Bolivia, South America's poorest nation, enacted one of the region's harshest anti-inflation and austerity packages, reducing annual inflation from a spurt of 24,000 percent in 1984 to 15 percent now.

Because of the free-market economic package, coupled with a return to democracy, Bolivia was hailed by the United States and others. But the economy is stagnant and unemployment is climbing.

"If the current crisis is not resolved, the political climate deteriorates," said Herbert Muller, an economist who publishes an economic newsletter. "To move forward, we need investment. We need to move investors past the wait-and-see attitude, and we are not doing that. We are going backwards."

The conflict began immediately after the May 1989 presidential and congressional elections, when no party won 50 percent of the vote and the election of the president was thrown to the Congress.

Paz Zamora's Revolutionary Leftist Movement (MIR), which finished third in the voting, allied with the rightist Nationalist Democratic Action (ADN) party, which finished second, to deprive the first-place finisher, the Nationalist Revolutionary Movement (MNR) of the presidency and a majority in both houses of Congress.

The MNR alleged massive fraud, but the Supreme Court, although controlled by the MNR, never moved on the party's petition to nullify the voting in three of the nation's nine departments where the MNR alleges it was cheated out of three senatorial seats -- enough to deprive the governing coalition of its majority in the Senate.

As relations between the parties deteriorated, the court ruled earlier this month that a new law raising taxes on beer was unconstitutional and agreed to study an MNR petition to declare a law on oil and mineral exploration in certain areas of the country unconstitutional.

The decisions cost the government $50 million in lost taxes and nine signed contracts for mineral and oil exploration were left in limbo.

The governing alliance called the ruling blatantly political and alleged that the court -- the only branch of government controlled by the MNR -- was seeking to sabotage the government's economic program.

When Congress threatened to impeach the eight judges affiliated with the MNR, the court dusted off the 19-month-old MNR petition to nullify part of the election results, and agreed to admit it to the court for study.

Ernesto Poppe, one of the eight impeached judges, announced Thursday he was going on an indefinite hunger strike in his chambers to protest the congressional action.

At the same time, Edgar Oblitas, president of the Supreme Court, saying that the nation was facing an "institutional coup d'etat," asked the military to give its members special protection "to avoid any attack on the court or any use of force against its members." The military refused the request.