RIO DE JANEIRO ? During the 1990’s, only one president of a country in the Americas was overthrown in a coup: Jean-Bertrand Aristide of Haiti, who was toppled by his military in 1991 and was granted exile in the United States. Since 2000, however, six elected heads of state have been ousted, including Mr. Aristide again last month. This time he claimed that the United States forced him into exile.

The new precariousness of elected leaders suggests that an epidemic of instability is again sweeping Latin America. But some leaders in the region are wondering privately whether President Bush has retreated from the American commitment to strengthening their political and economic institutions, a policy of Democratic and Republican administrations for two decades.

Shortly before he left office in 2003, President Fernando Henrique Cardoso of Brazil said in an interview on Mexican television that became famous throughout the region that President Bush “knows nothing about Latin America” and “doesn’t have the same web of contacts in the region as previous administrations.”

“The first time I talked with President Bush, he showed a complete hands-off attitude” about defending free markets and democratic values, Mr. Cardoso said, adding, “Since we are not a threat, we have been consigned to irrelevance.” Today, expressions of such attitudes are a staple in the region’s press, and they worry some American experts on Latin America.

To such thinkers a pattern seems to have emerged in which the United States does not come to the rescue of friends of democracy and American policies like Gonzalo Sánchez de Losada in Bolivia or Fernando de la Rúa in Argentina, even as it acts to help bring down leaders it cannot stomach, like Mr. Aristide and President Hugo Chávez of Venezuela.

Roger Noriega, the Bush administration’s assistant secretary of state for inter-American affairs, argues that nothing could be further from the truth. While “we have made a conscious decision that we can’t bail out every government that gets itself into financial trouble,” he said in a telephone interview from Washington, “we are committed to promoting and defending representative democracy across the political spectrum.”

But a contrast with previous administrations remains. When Jamil Mahuad, the president of Ecuador, was toppled in January 2000 by a coalition of Indian groups and military officers, the Clinton administration told the junta members succeeding him that theirs would be a pariah government, cut off from aid and recognition. As a result, power passed within hours to the vice president, Gustavo Noboa, and the United States was credited with helping preserve constitutional order.

No such message seems to have been sent in April 2002, when military and business leaders in Venezuela briefly overthrew and jailed Mr. Chávez. Instead, the United States argued that he had resigned, and it endorsed the new government. As things worked out, the new government collapsed within a day, bringing Mr. Chávez back to power. But even though he survived – more intransigent than ever and suspicious of any opposition – the United States was seen in the region as having backed a coup attempt.

Since the outset of the war on terror, Washington has seemed to many in Latin America to be disengaged from the region except when a crisis forces it to react.

“This administration has been much less interested in Latin American and Caribbean issues than previous ones,” said Robert S. Gelbard, a former career State Department official who held senior posts in the administrations of Presidents Ronald Reagan, George H. W. Bush and Bill Clinton. “It is less committed, involved and willing to pour political energy into the process of consolidating democracy.”

The first Bush administration helped organize an embargo against the government that overthrew Mr. Aristide in 1991, insisted that President Alberto Fujimori of Peru call elections after he dissolved Peru’s congress and helped broker an end to El Salvador’s civil war.

It also created a plan to help Latin America out of its financial crises, a stance the Clinton administration endorsed when Mexico was in danger of collapsing late in 1994. But when Argentina imploded in 2001, the current Bush administration largely stood on the sidelines.

“There was a consensus of the international community that Argentina had dug itself into a fiscal hole and was not going to be able to dig itself out just by plowing a lot more loans and debt onto the heads of the Argentine people,” Mr. Noriega said in explaining that policy. “But they are digging themselves out now with our help, making progress and turning the corner.” The United States did press for the International Monetary Fund to roll over Argentine debt, but has not provided cash aid.

Mr. Sánchez de Losada was overthrown last October by a coalition of Indian and labor groups. He is an enthusiastic advocate of free markets who supported an American war on drugs that many Bolivians disliked. Yet after he personally warned Mr. Bush of rising discontent at home and asked for $150 million in emergency aid, Bolivia received only $10 million.

“There was lots of verbal support, but when it came down to the hard facts, the money was not there, and it still has not emerged,” said Miguel Diaz of the Center for Strategic and International Studies in Washington, who in general likes Mr. Bush’s policies in the region.

As the cases of Argentina, Bolivia and Haiti indicate, the threat to stability today bears little resemblance to the classic Latin American military coup. Instead, the model is one of a popular uproar that forces an elected but unpopular (and in Mr. Aristide’s case increasingly autocratic) leader to step down.

So while leaders may no longer look over their shoulders at the barracks, they have to worry about being thrown out of office because an impatient citizenry expects immediate results from a weak state with weak institutions. “That’s an extremely disturbing attitude, because it provides no incentive to engage in democratic politics” and “only emboldens and heartens groups that are more interested in violence,” said Michael Shifter of Inter-American Dialogue, a Washington-based group.

In 1991, the Organization of American States adopted rules for cooperative action in an effort to assure that the turn to democratic rule would be made permanent.

Now, in Venezuela and Haiti, the Bush administration has been criticized for failing to support that policy. In Haiti, it focused more on detaching Mr. Aristide from the levers of power than on shoring up democracy with new political institutions and help for the economy. “They think they have solved the problem by getting rid of a leader, when the problem is far more complex” in Haiti, said Arturo Valenzuela, the National Security Council’s director for Latin America under President Clinton. “My fear is that what we’ve done now is to create a Perón, who will always be there, forever and ever.”