Shortly after taking office, President Obama declared Brazil’s charismatic president Luiz Inacio Lula da Silva “the most popular politician on Earth.” And Lula said he was “a fan” of Obama’s.

The relationship held the promise of a closer alliance between Washington and Brasilia. But it soon soured, with Lula saying at the end of his term that the United States behaved as an “empire” and that “nothing had changed” under Obama.

Now, Obama and Brazil’s new President Dilma Rousseff will try to repair at times strained relations between the two countries as the U.S. president arrives for a two-day state visit before flying to Chile, a close U.S. ally, and El Salvador, where drug-related violence is rising.

“There’s positive interest on both sides in starting over,” said Julia Sweig, a scholar at the Council on Foreign Relations who recently met with officials in the new government in Brazil. “Now they have to translate that optimism and goodwill to figure out what they can do together that’s in both of their interests, and how to mitigate the tensions that will naturally arise.”

The trip will be Obama’s first to South America as president. Even as the crisis in Japan and unrest in the Middle East dominate Obama’s national security briefings, administration officials decided not to cancel the president’s trip but instead cast it as a way to renew relations with a region that is an emerging market for U.S.-made goods.

The trip is in part a kind of box-checking exercise, as the Obama administration had wanted to make a major trip to this region in Obama’s first term. But White House officials said they would use Obama’s visit to the three countries, particularly Brazil, to emphasize economic issues, in a nod to a U.S. electorate concerned about high unemployment.

On Saturday in Brasilia, Brazil’s capital, Obama will attend a meeting of chief executives of companies from both countries and speak at a business forum.

Administration officials are also likely to privately press Brazil and the rest of South America to get involved in the U.S. effort to change how China values its currency. Treasury Secretary Timothy Geithner was in Sao Paulo discussing the issue last month.

“This trip fundamentally is about the U.S. recovery, U.S. exports and the critical relationship that Latin America plays in our economic future and jobs here in the United States,” said Michael Froman, deputy national security adviser for international economic affairs.

Veering from Lula’s model

Brazil is the most influential country in this region, and U.S. officials, while playing down any tensions with Lula, have expressed optimism about establishing close ties with Rousseff. The 63-year-old economist, who had once been in a guerrilla group, was brutally tortured by Brazil’s dictatorship in 1970 and later became Lula’s protege, serving as energy minister and then chief of staff.

A month before her Jan. 1 inauguration, Rousseff suggested she could veer from Lula’s model in dealing with the United States. Lula would not support a U.S. plan last year to impose U.N. sanctions on Iran for its nuclear program or a U.S.-sponsored U.N. resolution that condemned Iranian practices on human rights.

Although she is unlikely to support sanctions, the new president told The Washington Post in an interview in December that she disagreed with Lula’s position on Iran’s human rights record and that her government would “forge closer ties with the U.S.”

“She has been very positive about the type of relationship she wants to pursue with the United States, so we see an enormous moment of opportunity here,” said Ben Rhodes, deputy national security adviser for strategic communications at the White House.

To be sure, Rousseff’s new foreign minister, Antonio Patriota, a former ambassador in Washington, said in a recent speech that Brazil would continue to engage countries far from this region, “but not to the detriment of close relations” with the developed world, including the United States.

“There’s a different attitude, a desire for a much more pragmatic relationship with the United States,” said Cynthia J. Arnson, director of the Latin American Program at the Woodrow Wilson International Center for Scholars in Washington. “There’s a sense of a more pragmatic president, less ideological.”

Tensions on some key issues

Some analysts also note that this is the first time a high-level dialogue between the two countries will begin with a visit by a U.S. president.

“It’s symbolically important because Brazil is a new quantity in the world,” said Paulo Sotero, director of Wilson’s Brazil Institute.

Yet Sotero said Brazil also sees itself as a global player with its own agenda, meaning that tensions are likely to remain on some key issues.

Now the seventh-largest economy with diplomatic ambitions to match, Brazil has broader foreign policy goals including forging closer diplomatic and economic ties with countries like Russia and China, opposing the U.S. embargo on Cuba and battling the U.S. farm subsidies that effectively keep vital Brazilian agricultural products out of the U.S. market.

“I wonder whether the U.S. government and Obama will be expecting too much from Brazil,” said Luiz Felipe Lampreia, a former Brazilian foreign minister and author of “Brazil on the Wings of the World.” “I think it is absolutely unrealistic to expect that Brazil will become a partner of the United States.”

Rousseff has publicly said her priorities will not be the foreign policy issues that at times have divided the United States and Brazil, but instead domestic concerns such as lifting 14 million people out of extreme poverty, slicing debt and improving substandard infrastructure, vital for an economy increasingly dependent on global trade.

To achieve those and other goals, analysts say, Rousseff’s government needs heavy foreign investment from countries such as the United States. Brazil cannot afford to send an inconsistent message abroad, said Sotero, explaining how some policy makers in the new government believed Lula’s effort to resolve the Iran nuclear crisis “was not a productive initiative for Brazil.”

Bacon reported from Washington.