NEWS ANALYSIS : An Angry Brazil Braces for Collor’s Last Stand : Politics: Impeachment proceedings could bring drawn-out legal wranglings. Some fear a military move.

President Fernando Collor de Mello, under threat of impeachment and pressure to resign, is preparing to make his last stand.

The crisis that engulfs Collor, 43, has this huge nation trembling with anger and anxiety. There is, it seems, no easy way out for him or for the country.

Even if Collor avoids impeachment, his administration will be crippled, most analysts agree. Some fear tumult in the streets and military intervention if the public perceives that justice has not been done.

A report on corruption, linking Collor to a massive influence-peddling racket, is expected to be approved by a congressional investigative committee today. Then, within two weeks, the Brazilian bar and press associations plan to submit a formal request for the president’s impeachment.

Collor has repeatedly denied any wrongdoing, but public opinion has turned against him. Pro-impeachment demonstrations have become daily events.

The public outrage is turning former Collor allies in Congress against him. They don’t want their parties to be associated with a reviled president when nationwide municipal elections are held in October.

The president’s advisers are now urging him to make a dramatic play for popular sympathy, press reports say. The idea is for Collor to go on national television, confessing his errors and explaining that he was betrayed by the associates who are accused of corruption.

Then, once the request for impeachment is submitted to the lower house of Congress, Collor’s aides are expected to begin a preemptive legal battle. Their best hope apparently is to ask the Supreme Court to confirm that parts of Brazil’s 1950 impeachment law are incompatible with provisions for impeachment in the 1988 constitution.

In 1989, the Supreme Court made a similar ruling in the case of an attempt to impeach Jose Sarney, Collor’s predecessor.

Legal maneuvering could take weeks, maybe months. If it fails, Collor will need one-third of the 503 lower house votes to block impeachment. If he loses, jurists say, he will be suspended from office for 180 days while the Senate or the Supreme Court tries his case.

Vice President Itamar Franco, an independent, is constitutionally designated to assume the presidency in Collor’s absence. But some politicians fear a near-vacuum of power under Franco, who has little political support and whose economic ideas are said to displease Brazil’s business elite.

Brazil’s current recession could deepen, and its chronic inflation, now running at more than 20% a month, could rage out of control, many analysts fear. They warn that as the severe economic problems become even worse, popular discontent could explode.

Discontent already is deep, partly as a result of disappointment in Collor. He is the first president elected by popular vote in three decades. He had promised to stop inflation, fight government corruption and reduce bureaucratic abuse.

If allowed to finish his term, which ends in 1995, he would face an outraged public with little understanding of the legal or political intricacies that saved his job.

“There could be social unrest in which the villain would be the Congress,” said Sen. Jarbas Passarinho, who was Collor’s justice minister until early this year. “That could generate violent street disturbances.”

Then, the army might find it necessary to intervene--”not to make a coup but to maintain order,” Passarinho said. “And from there you can no longer predict what will happen.”

Opposition politicians, of course, would prefer that Collor resign. “I think that very probably it will come to that,” said opposition Sen. Pedro Simon, recalling former U.S. President Richard M. Nixon’s resignation. “The process of impeachment is too dramatic, too long.”