By Todd Benson

SAO PAULO, March 6 (Reuters) - U.S. President George W. Bush visits Latin America this week to try to improve his reputation and influence in a region where anti-American voices like Venezuela's President Hugo Chavez are on the rise.

Bush is expected to cozy up to moderate leftists like Brazil's President Luiz Inacio Lula da Silva, hoping to woo him with a much-touted plan to cooperate on the production of biofuels like ethanol.

"This is basically an effort to show that the U.S. remains relevant in the region," said Peter Hakim, president of the Inter-American Dialogue, a think tank in Washington.

"It's a trip to demonstrate that it retains good relationships, particularly with Brazil and Mexico, that it's committed to Colombia, and that it's not worried about left-wing governments."

Bush will kick off his tour on Friday in Brazil. He will then travel to Uruguay, Colombia, Guatemala and Mexico on the six-day trip, his longest ever to the region.

Chavez, the fiery Venezuelan president who is challenging U.S. influence in Latin America, plans to protest Bush's presence in the region by leading a rally in Argentina on Friday when his nemesis will be in neighboring Uruguay.

It is no coincidence that Bush's tour starts in Brazil, a heavyweight with the clout to contain Chavez. Though Bush and Lula come from opposing sides of the left-right divide, they are folksy leaders with a good rapport.

Other important stops will be Colombia and Mexico, two close U.S. allies. In Bogota, Bush is expected to reaffirm his support for President Alvaro Uribe, who is fighting a decades-old insurgency and is a partner in the war on drugs.

The visit to Mexico will be Bush's first since President Felipe Calderon took office in December. Analysts expect key bilateral issues like drugs and immigration to be high on the agenda.

ETHANOL DIPLOMACY

In Sao Paulo, officials say Bush and Lula will launch a biofuels initiative aimed at helping Brazil export its ethanol technology to the region. Washington hopes it will help the United States reduce its dependence on Middle Eastern and Venezuelan oil.

But some in Brazil wonder if the initiative will bear fruit. They say that if Washington wants to promote biofuels, it should scrap the 54-cents-a-gallon tariff it levies on Brazilian ethanol imports -- a politically sensitive issue that Bush is unlikely to budge on.

"If the United States wants to talk ethanol, let's talk import tariffs," said Pedro Camargo Neto, a former official at the agriculture ministry. "The rest is just playing games."

While the United States is waking up to ethanol, Brazil is a biofuels pioneer. All gasoline here is blended with ethanol made from sugar cane and over 80 percent of new cars are flex-fuel, which run on gasoline or ethanol.

Brazil also has domestic political reasons to warm up to the United States. Lula has been criticized since Brazil's former ambassador to Washington accused the government of letting anti-U.S. sentiment prevent closer economic ties.

Lula will follow up Bush's visit with a trip to Washington on March 31, prompting some Brazil watchers to say it appears the two countries are growing closer.

Still, some question if Bush's ethanol diplomacy is enough to counter the checkbook diplomacy of Chavez, who has been handing out petrodollars to like-minded leaders in the region.

Bush, who vowed in 2000 to make Latin America a "fundamental commitment" of his presidency, is now being criticized by Democrats for having "lost" Latin America.

On Bush's watch, Venezuela swung to the left and Chavez-backed candidates won office in Bolivia, Ecuador and Nicaragua.

And while Washington has been focused on the war in Iraq, which is very unpopular across much of Latin America, China has emerged as a major trading partner for the region.

"The United States is not the go-to guy anymore from the Latin American perspective," said Julia Sweig, a Latin America specialist at the Council on Foreign Relations in New York.

(Additional reporting by Reese Ewing)

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