By Daniel Schweimler
BBC News, Buenos Aires
It was the kind of situation that the Venezuelan leader, Hugo Chavez, loves - 40,000 flag-waving supporters joining him in hurling insults at the US President, George W Bush.
Chavez attacked Bush in front of the Buenos Aires crowd
He was at a football stadium in the Argentine capital, Buenos Aires, leading what he called an anti-imperialist rally to coincide with Mr Bush's arrival in neighbouring Uruguay.
Most of the crowd were members of trade unions, left-wing and human rights organisations, those who already supported Mr Chavez and what he calls his brand of socialism for the 21st Century.
Others had come simply out of curiosity to see with their own eyes the man who was grabbing so many headlines - the man who dares to stand up and insult the leader of the most powerful country in the world.
Marcos said: "I am here because I think it is necessary to demonstrate against not only the USA but also against the policies that put at risk lives in the countries they conquer and in the whole world. We have to demonstrate."
Graciela added: "I think Chavez has many good things although I don't agree with him 100%. But, if I had to choose between the two I do know I prefer Chavez and that is why I am here."
Loud and clear
Chavez was in his element as he addressed the crowd
All the main left-wing groups waved their huge flags, making it difficult for many to see the Venezuelan leader on the stage. But the powerful sound system ensured that they had no problems hearing him.
Families with small children brought picnics and groups of friends joined in the insult hurling on a balmy evening.
Buses that had brought thousands from the outlying regions of Buenos Aires lined the neighbouring streets.
Mr Chavez, in his customary red shirt, called Mr Bush a political corpse and, in his best English, repeated what has almost become his regular slogan: "Gringo, go home!"
Filling a void
There is little doubt that the two men are battling for hearts and souls in Latin America. When President Bush took office he said Latin America would be a priority. Then came 9/11 and Washington's focus shifted to the Middle East.
Many analysts accuse the United States of neglecting their own backyard. That's a charge the US president denies although he did say his tour of Brazil, Uruguay, Colombia, Guatemala and Mexico was designed partly to put his message across more clearly.
Hugo Chavez has moved quickly to fill the void left by the United States. He strikes a chord with many in Latin America's shanty towns and leaders in the region can't afford to ignore him.
But many also want to stay on the right side of Washington and the Argentine president, Nestor Kirchner, was not at the anti-imperialist rally, neither were senior members of his government.
He may agree with much of what Mr Chavez says but still wants to deal with the United States and many leaders in the region are trying hard to stay friends with both men, not easy when they are so far apart on the political spectrum.
Mr Chavez moves on to Bolivia for a meeting with one of his main allies in the region, President Evo Morales, to continue talking about Latin American integration.
President Bush expected protests. He said he welcomed the demonstration of free speech.
But he might not have expected them to be so ferocious and knows he has got his work cut out if he is going to convince Latin Americans that the United States, and not Venezuela, should be leading the way forward.