Thousands of protesters were arriving at this seaside resort, seizing the chance to criticize President Bush over his push for unfettered free trade and a new trade zone stretching from Alaska to Argentina.
Mr. Bush was to arrive late Thursday in Mar del Plata for the fourth Summit of the Americas, a two-day gathering with 31 fellow leaders from Latin America and the Caribbean.
The focus of the summit Friday and Saturday is how to create jobs for a region where unemployment and underemployment has been a prime concern for decades.
Mr. Bush also wants to re-ignite talks stalled for years over the creation of a Free Trade Area of the Americas that would overtake the European Union as the world's largest trade zone.
On Wednesday, however, government officials at the summit site were still bickering over whether the event's final declaration would include key language on when high-level FTAA negotiations might resume.
Victor Hugo Varsky, an Argentine negotiator, said negotiators were "advancing very slowly" as they decide what priority the FTAA should have in that statement.
"Some countries don't want any mention," he said. "Others want to progress toward a trade accord."
Demonstrators at the People's Summit — and Venezuelan President Hugo Chavez and top Cuban government officials — say Mr. Bush is bent on opening up Latin America even more to corporations that will end up enslaving already poor workers.
"Latin America remains the region of most inequalities in the world," Cuban Foreign Minister Felipe Perez Roque told The Associated Press in Havana as a Cuban delegation gathered at a "People's Summit" to counter the Americas Summit. "The FTAA is just more of the same neo-liberal policies."
Communist-run Cuba, an adversary of the United States for more than four decades, is the only country in the hemisphere that was not invited to the summit hosted by the regional Organization of American States.