RIO DE JANEIRO (AP) — Front-running presidential candidate Marina Silva says the key to her support among millions of Brazilians who joined in anti-government protests last year is her understanding that reforming a broken political system will come from the ground up.

Silva spoke exclusively with The Associated Press on Wednesday in her first interview with a foreign media outlet since being thrust into a hotly contested campaign just a month ago, after her Socialist Party's first candidate died in a plane crash Aug. 13.

In a wide-ranging, hour-long interview, Silva said that as president she would seek bilateral trade deals and better relations with the U.S. and Europe, and would push for improved human rights in allies such as Cuba.

Asked what she would do to lessen Brazilians' frustrations with an inefficient political system widely viewed as corrupt, Silva said real change won't come from the top.

"It's neither the parties nor the political leaders who will bring about change," she said. "It's the movements who are changing us."

A former Amazon activist and environment minister who pushed policies that helped Brazil slash the rate of jungle destruction, Silva is in a dead-heat presidential race with incumbent Dilma Rousseff. Rousseff represents the Workers Party, which Silva herself helped found three decades ago.

"Brazil has a great opportunity to become a global leader by leading by example," Silva said in talking about human rights and environmental protections. "Our values cannot be modified because of ideological or political reasons, or because of pure economic interest."

Asked whether she would continue Brazil's strong investment in and political support for regimes like Cuba, Venezuela, China and Iran, Silva said that dialogue is essential with each — but that her personal convictions mean Brazil would be more vocal in pushing human rights.

"The best way to help the Cuban people is by understanding that they can make a transition from the current regime to democracy, and that we don't need to cut any type of relations," she said. "It's enough that we help through the diplomatic process, so that these (human rights) values are pursued."

Brazil's relationship with the U.S. has been chilly since revelations more than a year ago that the National Security Agency's espionage programs targeted Rousseff and other Brazilian officials.

After the revelation, Rousseff cancelled her earlier acceptance of President Obama's invitation for a formal state visit — the first time in memory a foreign leader rejected the honor.

Silva said the U.S. spying was a grave and intolerable error, but she added that it is time to move on.

"Both nations need to improve this situation, to repair the ties of cooperation," she said. "The Brazilian government has the absolute right to not accept any such interference. But we also cannot simply remain frozen with this problem."

The presidential vote is Oct. 5, but the contest likely will go into a second-round ballot between Rousseff and Silva three weeks later since neither is expected to win an absolute majority in the first round of eight candidates.

Silva, who could become Brazil's first black leader, has deep roots in Brazilian politics but has tapped into an anti-establishment mood, a roiling frustration with government that erupted in huge street protests in hundreds of cities last year demanding top-to-bottom change.

Silva's life story connects with millions struggling to keep modest advances made as Brazil boomed in the first decade of this century.

Born to an impoverished rubber tapper in the remote Amazon jungle state of Acre, Silva grew up illiterate and collected latex from trees from dawn to dusk. She nearly died as a child and said her family often had virtually nothing to eat.

She was infected with malaria five times and suffered from leishmaniasis, a disease that causes skin ulcers and other ailments. When she was 15, her mother died. At 16, she was sent to the state capital, Rio Branco, for hepatitis treatment — and to finally learn to read and write.

Deeply religious and now an evangelical Christian, Silva at that age wanted to become a nun. She went to study in a convent, and there met priests adhering to liberation theology, a Latin American-inspired movement that advocates for the poor.

It was her political awakening. She joined the Workers Party in its early days and was elected a Rio Branco city council member in 1989. Two years later, she moved into the state legislature before becoming a federal senator in 1995. President Luis Inacio Lula da Silva, who is no relation, made her the environment minister when he took office Jan. 1, 2003.

"If elected, she has such a remarkable personal story that she'd come to the presidency with a lot of legitimacy, tremendous excitement and high expectations," said Michael Shifter, president of the Washington-based Inter-American Dialogue.

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Brad Brooks on Twitter: www.twitter.com/bradleybrooks