BRASILIA, DEC. 3 -- President Bush today opened a six-day visit to Latin America designed to promote democracy, but his aides spent much of the day trying to decide whether a military uprising in Argentina, which ended in failure this evening, would prevent him from visiting there later this week.

Bush's plane touched down in the Brazilian capital just before dawn, and he was immediately greeted with reports about the rebellion by soldiers in Buenos Aires. Administration officials, determined not to let anything spoil Bush's visit to the region, offered a public show of bravado, with Bush saying he had "no plans" to change his schedule. Bush also offered a statement of support for Argentine President Carlos Saul Menem.

"We are not going to let this be drawn out of proportion," Deputy Secretary of State Lawrence Eagleburger told reporters early in the day. Asked if the uprising demonstrated the fragility of democracy in a region with a history of military governments, Eagleburger said, "It shows nothing of the sort, if it's put down fairly quickly, as we expect."

The officials traveling with Bush maintained contact with the U.S. ambassador in Argentina, Terence A. Todman. As the day progressed, some members of the traveling party privately expressed concern about the continued fighting and the lack of clear information, and their assurances about Bush's schedule became more tentative.

But about the time the last of the rebels surrendered, Fitzwater announced that the press corps would proceed to Buenos Aires on Tuesday night, as planned. Bush is scheduled to arrive Wednesday morning, after an overnight stop in Uruguay.

The uprising in Argentina was a new disruption for the Bush visit. The president postponed the trip in September because of the Persian Gulf conflict and budget negotiations in Washington. With no major agreements to sign and little new to offer the South American governments, Bush's purpose was principally to promote his Enterprise for the Americas Initiative and laud the fact that most of the countries in the hemisphere are now democratic.

Bush compared the changes underway here to the dramatic transformation of Eastern Europe. In a speech to a joint session of the Brazilian Congress, the president also promoted his proposal for a free-trade zone stretching from Canada to the southern tip of South America. "We see a future where growing opportunity, the power of technology and the benefits of prosperity are developed and shared by all," he said.

He also said the Iraqi invasion of Kuwait had put severe pressures on many of the economies in the region and explained that that was a reason to bring the crisis to a resolution as soon as possible. Noting that higher oil costs will drain $5 billion from Brazil's weakened economy in the coming year, he said, "That's why people say to me, 'Well, this can go on and on and on,' and I say no."

The situation in the Persian Gulf kept Bush's top advisers in Washington. Secretary of State James A. Baker III, national security adviser Brent Scowcroft and White House Chief of Staff John Sununu all skipped the trip, which also includes stops in Chile and Venezuela.

In private talks with President Fernando Collor de Mello today, Bush said the administration would allow the Brazilians to purchase a supercomputer that critics said could be used to help develop nuclear weapons or ballistic missiles. The sale will not become final until the two nations agree on safeguards.

Brazil and Argentina said last week that they would jointly take steps to assure that their nuclear programs meet international safeguards and would not be used for military purposes, an announcement that helped persuade Bush to let the computer sale go ahead.

Brazil's foreign debt also was a major topic of discussion between Brazilian and U.S. officials, including Treasury Secretary Nicholas Brady. Bush got a firsthand view of the strong feelings in Brazil about the debt, which totals more than $100 billion owed to governments and commercial banks around the world.

In a speech welcoming Bush to the Congress, Brazil's Senate majority leader, Ronan Tito, said debt payments in the 1980s had helped to impoverish the country. "Brazil invites our creditors to become partners in our development and growth, not partners in our poverty," he said.

Bush's Enterprise for the Americas Initiative offers some relief on the roughly $12 billion owed to the U.S. government.