Bush's trip is widely seen as offering a counterpoint to the populist appeal of Venezuelan President Hugo Chavez, whose nationalization plans he criticized.

"I strongly believe that government-run industry is inefficient and will lead to more poverty," Bush said when asked about Chavez's nationalizations.

"If the state tries to run the economy, it will enhance poverty and reduce opportunity."

Bush also made clear he is keeping an eye on Cuba and its long-time leader.

Castro, 80, was forced to temporarily hand power to his brother, Defense Minister Raul Castro, last July after stomach surgery. He mostly stayed out of view until a surprise live radio appearance last week.

Castro's fate will be decided "by the Almighty," Bush said on Tuesday.

"I don't know how long he's going to live but nevertheless I do believe that the system of government that he's imposed upon the people ought not to live if that's what the people decide," he told reporters representing the countries he will visit.

Bush took a dim view of the possibility of Raul Castro taking over permanently.

"What I hope happens is that we together insist that transition doesn't mean transition from one figure to another, but transition means from one type of government to a different type of government, based upon the will of the people," he said.

Bush leaves on Thursday for Brazil, first stop on the six-day tour that will include visits to Uruguay, Colombia, Guatemala and Mexico.

He takes a softer message aimed at improving his reputation and bolstering U.S. influence in a region where anti-American voices like Chavez are rising.

Bush carefully avoided mentioning the fiery Venezuelan leader's name, particularly when asked about Chavez's plans to hold a protest rally in Argentina while he is in neighboring Uruguay.

"My attitude is, I love freedom and the right for people to express themselves," Bush said. "I bring a message of goodwill to Uruguay and to the region. My trip is one that says, let's find ways to work together for the common good."

Pushing free trade and open markets, Bush rejected the development model championed by Chavez that calls for nationalization of industry and greater government intervention.

"I fully recognize that until people actually feel progress in their pocketbook that 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," he said.

While Bush is trying to make friends with more moderate leftist leaders in Latin America, he also will check in on a strong ally in the war on drug trafficking, Colombian President Alvaro Uribe.

A scandal tying allies of Uribe to paramilitary gangs has Democrats questioning U.S. aid and trade deals.

Washington has given $4 billion to "Plan Colombia" since 2000 to help fight the country's cocaine-fueled insurgency, but Democrats are monitoring the scandal as they review a White House request for $3.9 billion in new aid.

Bush said even though the proposal is a slight reduction, he will vigorously defend it to the U.S. Congress.

"I look forward to telling President Uribe that he can count on the United States defending that which we sent up to Congress," Bush said.