Andres Oppenheimer is a Tribune Media Services columnist.

President Barack Obama's announcement that he will visit Brazil, Chile and El Salvador in March -- in what will be his first trip to South America -- could result in an improvement in Brazil-U.S. ties following a significant downturn over the past two years.

Obama announced in his State of the Union address to Congress Tuesday that he will visit the three countries as part of his efforts to strengthen ties with Latin America. The five-day visit is likely to take place in the second half of March.

There is little question that Brazil, the world's eighth-largest economy and an emerging global power, will be the most important leg of Obama's trip. Tensions between Brazil and Washington rose during the last two years of former Brazilian President Luiz Inácio Lula da Silva's administration over, among other things, Brazil's diplomatic support of Iran.

But now, after the Jan. 1 inauguration of Lula da Silva's hand-picked successor, Dilma Rousseff, a former leftist guerrilla who served as his chief of staff, U.S. officials are hopeful that they will be able to rebuild bilateral ties.

In a telephone interview, Dan Restrepo, senior White House advisor on Western Hemisphere affairs, told me that Rousseff "has made quite clear in her public statements that she is looking forward to continuing and strengthening our ties. One of the reasons we are going to Brazil this early in her presidency is that we see an opportunity to continue and deepen the relationship at the highest level."

Restrepo did not elaborate, but other Brazil watchers see several signs that Rousseff's foreign policy may be less hostile to Washington than her predecessor's was in his last years in power. Among the signs:

- Rousseff has taken distance from Lula da Silva's diplomatic love affair with Iran. Among other things, she did not endorse his failed mediation effort over Iran's nuclear program, and suggested that she doesn't agree with her predecessor's decision not to condemn Iran's human rights abuses.

- Brazilian and U.S. officials have cooperated more closely in recent weeks in trying to resolve Haiti's political crisis stemming from disputed November elections, according to U.S. diplomats familiar with the negotiations.

- The new Brazilian president picked Antonio Patriota, a respected former Brazilian ambassador to Washington, as her foreign minister. Patriota indicated in a recent speech that Brazil will continue strengthening ties with other developing countries, but "not at the expense" of worsening ties with the United States and Europe.

- Rousseff is said to have been moved by U.S. Secretary of State Hillary Clinton's decision to attend her inauguration ceremony on Jan. 1, despite the fact that Clinton had to board her plane at dawn with little time to rest after New Year's Eve celebrations.

"There are clear signs of change in Brazil regarding an effort to reconnect with the United States," said Paulo Sotero, head of the Brazil program at the Washington, D.C.-based Woodrow Wilson International Center for Scholars. "This is a new moment in the relationship, following the episodes that had caused so much damage over the past two years."

U.S. officials say that in Brazil, Obama will discuss cooperation plans on clean energy, reconstruction aid for Haiti, and citizens' security, including U.S. offers to share know-how on security issues in anticipation of the 2014 World Cup and the 2016 Summer Olympics in the South American country.

My opinion: I was surprised to hear that during his trip, Obama will not stop in Colombia, the closest U.S. ally in the region in recent years. U.S. officials tell me that is because Obama will attend the Summit of the Americas in Cartagena, Colombia, in April 2012, and will most likely stay on for an official visit to that country. Maybe so.

For the time being, all eyes of the region's diplomatic community will be on Obama's visit to Brazil.

There won't be any dramatic change and Brazil will continue its policy of developing ties with the Third World as a way to consolidate itself as a new global power. But considering Brazil's weight in the region, even a small move toward closer ties with Washington will have a significant impact on U.S.-Latin American relations.