Bush begins his tour in Brazil where he will meet the country's president Lula de Silva.
Members of Lula's Workers Party are not as welcoming as their leader however, and plan to hold an anti-Bush protest.
Ricardo Berzoini, the party president, said they will "demonstrate their disagreement with the way the United States behaves itself in the world".
Brazil's female trade unionists are also planning an anti-Bush protest in Sao Paulo to mark international women's day.
On Friday, Bush arrives in Uruguay, where demonstrations have been organised by the national labour federation and an umbrella organisation of radical groups.
Fernando Pereira, a spokesman for the labour federation, said that unions were planning a march against Bush because of "the lack of peace in the world".
|Bush can expect a fierce welcome |
from many Guatemalans [AFP]
But one of the biggest demonstrations this week is likely to the "anti-imperialist rally" organised by Chavez.
Bush has said that the Venezuelan leader's policies, which include nationalisation and state intervention, will only create more poverty in the country.
"I strongly believe that government-run industry is inefficient and will lead to more poverty," he said.
"So the United States brings a message of open markets and open government to the region."
"I fully recognise that until people actually feel progress in their pocketbook, there's going to be frustrations with forms of government. But that doesn't mean you kind of revert to something that I don't believe will work."
End to communism
Bush also said that when Fidel Castro dies, his communist government should also cease to exist.
"How long he stays on earth, that's a decision that will be made by the Almighty."
"How long he [Fidel Castro] stays on earth, that's a decision that will be made by the Almighty"
George Bush, US president
The US president expressed hope that the communist system cultivated during neraly five decades of rule by the 80-year-old Castro, would not persist after the ailing leader's death, if that is what Cuban voters wanted.
"I do believe that the system of government that he's imposed upon the people ought not live if that's what the people decide," Bush said.
"We believe it ought to be up to the people, the long-suffering people of that island, to decide their fate, not the fate, not to be decided because somebody is somebody's brother."
Castro underwent intestinal surgery in July and handed over power temporarily to his brother and the country's head of defence, Raul.