President Bush left a meeting of democratic leaders from the Western Hemisphere on Saturday hours before negotiators ended the summit without reaching an agreement on whether to revive talks on creating a regional free trade zone.

A senior administration official said two opposing views emerged at the summit: one favoring the proposed Free Trade Area of the Americas while acknowledging that many challenges need to be addressed before a deal can be sealed, and another saying that the conditions do not yet exist to make an agreement viable.

The official said that some of the problems, including disputes over U.S. farm subsidies and fears among Latin leaders that the economies of smaller nations would be overwhelmed by the United States, could be addressed in upcoming World Trade Organization negotiations.

The United States and 28 of the other 33 countries that participated in the talks had earlier signaled a willingness to continue the negotiations.

The pact, which Bush has maintained would help reduce poverty and boost economic growth, has drawn vehement opposition from some Latin leaders who say it would exacerbate large economic disparities across the region.

Five countries -- Venezuela, Paraguay, Uruguay, Brazil and Argentina -- declined to take part in the negotiations. President Hugo Chavez of Venezuela called the free trade agenda an "imperialist" plan being foisted on the region by the United States.

Before the summit ended, another Bush administration official had said that "the United States government feels very good about the discussions."

The official said Bush left the meeting after he and Secretary of State Condoleezza Rice had made their case for the pact. "We'd like to see the continuation of the free trade talks," the official added.

By the time Bush left this city Saturday afternoon for a meeting in Brasilia Sunday with President Luiz Inacio Lula da Silva of Brazil, the future of the negotiations was still uncertain.

By the time Bush departed Argentina, several other leaders had also left the meeting, leaving behind lower-ranking officials to attempt to hammer out a joint declaration hours after the summit's scheduled close.

As Bush flew to Brazil aboard Air Force One, a senior U.S. official tried to play down in a briefing with reporters the significance of whatever declaration emerges from the talks. "The success of the summit is not measured by the declaration," he said. "I think everyone would say the success of the summit is measured by the interchange among the leaders and whether they got greater clarity on the way forward."

The United States has encountered growing resistance in pushing its free trade agenda in recent years, as many countries in the region have voiced objections to what they say is unilateral U.S. foreign policy.