President George W Bush has said free trade would strengthen democracy in the Americas, in an address to the Organization of American States (OAS).
Mr Bush said everyone in the Americas had a right to democracy
He said a pan-American trade pact would unite the region in prosperity and reduce the risk of "false ideologies".
Earlier, the US secretary of state called on the OAS to bolster struggling Latin American democracies.
Several countries are said to be considering an alternative plan which some diplomats see as "less intrusive".
Ministers from 34 American and Caribbean nations are in Fort Lauderdale, Florida, to discuss the region's most pressing problems.
Mr Bush said a recent free trade deal between the US and Central American states provided "a historic opportunity to bring prosperity to people who have never known it.
"It is a signal of the US commitment to democracy and prosperity for our neighbours," he said, urging Congress to ratify the agreement.
He said he would continue to push for a pan-American deal.
"An Americas linked by trade is less likely to be divided by resentment and false ideologies," he said.
A proposal to create a Free Trade Area of the Americas has stalled over the issue of agricultural subsidies.
Mr Bush said the OAS charter guaranteed all people of the Americas "the right to democracy".
Nearly all Latin American countries have moved from dictatorship to democracy over the last three decades - but elected governments have still been liable to fall or be overthrown.
Opening the summit on Sunday, Condoleezza Rice called for greater intervention by the OAS in Latin America, highlighting concern over crises in Bolivia, Ecuador and Haiti.
Venezuelan President Hugo Chavez called the Bush administration's plan a ploy to justify US intervention in the region.
"The times in which the OAS was an instrument of the government in Washington are gone," he said.
Condoleezza Rice opened the meeting on Sunday
Venezuelan Foreign Minister Ali Rodriguez said OAS rules did not allow members to monitor the democratic processes of other states. Mexico has also expressed reservations.
Brazil and other countries have been putting together an alternative proposal.
"Democracy cannot be imposed. It is born from dialogue," Brazil's Foreign Minister Celso Amorim said.
But OAS Secretary General Jose Miguel Insulza, of Chile, denied the rival proposal amounted to a rejection of the US plan.
"There's been a discussion. I think we'll come out with something," he said.