President Bush’s coming visit to five Latin American countries starting March 8 will be his biggest effort ever to improve ties with the region, but the trip may come too late to counter Venezuelan President Hugo Chavez’s checkbook diplomacy and the growing anti-American sentiment in the region.

Bush, who during his 2000 campaign vowed to make Latin America a “fundamental commitment of my presidency” but later put the region on the back burner, will travel to Brazil, Uruguay, Colombia, Guatemala and Mexico. The six-day trip will be Bush’s longest to the region ever.

But Bush will visit the region as a weak president. The Latin American presidents who will receive him will be aware that he is a lame-duck leader with an opposition Congress, whose vice president is not running for president. In fact, this will be the first White House in 80 years with no candidate for the presidency.

Bush’s hosts also probably will know that the U.S. president will have little to say in the selection of his party’s candidate for the 2008 elections. Barring a sudden reversal of Bush’s political fortune, few Republican candidates will want to be seen with a president whose popularity has plummeted to 28 percent in the latest CBS News poll.

In addition, Bush will be arriving in Latin America only a few months before the July 1 expiration of his congressional authority to negotiate new free trade deals in an expedited way. His hosts know that an increasingly protectionist Congress – buoyed by cable television isolationist zealots such as CNN’s Lou Dobbs – may not extend the president’s so-called trade promotion authority.

Making things worse, Bush’s popularity in many countries, especially in South America, is as low as it can get.

“Bush goes to Latin America with a significant liability,” says Arturo Valenzuela, a former head of Latin American affairs at the Clinton White House. “It has less to do with U.S. Latin America policy than with a generalized rejection of the U.S. posture in the world, which makes it much more difficult for him to engage with the region’s leaders.”

U.S. officials shrug off these arguments, noting that the U.S. president has a unique power to start initiatives and speed up existing ones.

Some Bush supporters say that the very fact that he will be a bystander in the 2008 election will be a big plus for the Latin American countries he will be visiting: for the first time, a U.S. president will be able to talk with his southern neighbors without thinking exclusively about U.S. domestic politics, and taking a long-term view of what’s needed to improve U.S.-Latin American ties, they say.

Others say that Bush may also be able to make some concrete progress in Mexico, perhaps his most important stop, on issues such as drugs, migration and unresolved trade disputes over trucking rights and agricultural products.

“In Mexico’s case, it won’t be a public relations visit,” says Manuel Rocha, a former U.S. diplomat in several Latin American countries.

“The U.S. political establishment got really scared in the recent Mexican elections. Much like what happened in the former Soviet Union, there is a bipartisan consensus in Washington that Mexico deserves more U.S. attention because it’s a national security issue.”

My opinion: I don’t think Bush will be able to win many hearts and minds in Latin America while U.S. troops remain in Iraq and Chavez continues promising petro-dollars to any leader who is willing to be photographed with him.

If anything, Bush will be able to remind Latin American countries that the U.S. economy offers huge opportunities for them to increase exports, get more foreign investments and receive more tourists. To put things in perspective, just one U.S. state – Florida – has a $680 billion economy that is nearly three times bigger than the combined gross domestic product of Venezuela, Cuba, Bolivia, Ecuador and Nicaragua.

If Bush manages to convey the idea that the Chinese communists have long understood – which is that no matter what you think about Washington’s foreign policy, the United States remains the biggest buyer of the world’s goods and services – the U.S. president will be able to consider his trip a success.