And it may end with election of the country's first black president.
Silva's rise is all the more remarkable given that she was not in the running for the highest office until the August 13 plane crash that claimed the life of the Socialist Party's original candidate Eduardo Campos.
Silva, his running mate, was subsequently installed as the Socialist Party's challenger and is now tantalizingly close to ending the 12-year rule of Rousseff's Workers Party (PT).
Silva's election would cap a remarkable journey for the veteran environmental campaigner, who was raised in a community of rubber tappers in the Amazon and only learned to read and write at age 16.
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The presidential candidate of the Brazilian Socialist Party (PSB) for October's presidential ele …
Silva has her sights firmly set on surviving the first-round ballot next month to enter a runoff that most analysts project will give her a real chance of securing victory.
Unlike the first round of voting, Brazil's election laws grant candidates in any runoff the same amount of television and radio time -- a factor likely to benefit Silva's campaign.
The latest Datafolha opinion poll shows Rousseff widening her lead over Silva at the October 5 ballot, carving a seven-point margin from 37 percent to 30 percent.
However, a succession of polls have indicated the two rivals would be virtually neck-and-neck in a runoff, with many surveys suggesting Silva would be the likelier winner.
Daniel Alves, a political scientist at the Getulio Vargas Foundation, says that Silva's rags-to-riches backstory has struck a chord with millions of her compatriots seeking to lift themselves out of poverty.
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Brazil's presidential candidate for the Socialist Party, Marina Silva, and her vice presidential …
"Brazilians like to believe that everything is possible if you work hard and have faith," Alves told AFP.
"Marina Silva is mixed-race, was born and raised in the poor interior of Brazil, and now has a chance of becoming president of Brazil. She is the embodiment of the hope that Brazilians have."
- 'One egg and some flour, salt' -
Rousseff's allies however have attacked Silva, claiming that the presidential rival has the "face of a little saint" but would be likely to undo the Workers Party's social welfare programs that have raised living standards for millions of Brazilians over the past decade.
Silva has responded forcefully to the claims, insisting that her own humble beginnings prevent her from forgetting her obligations to the poor.
"Dilma, I am not going to stoop to fight on your level. Of course I am going to maintain family support payments, and do you know why? Because I was born in Seringal Bagaco (in Brazil's impoverished Acre state). I know what it is to feel hunger.
"The only food my mother sometimes had to feed eight children was one egg and some flour and salt, with a little bit of diced onion," she said.
"I remember once having looked at my father and at my mother," she continued, becoming emotional.
"I asked them, are you two going to eat? And my mother answered, 'No, we're not hungry...' but later I came to understand that there was more than one day that they didn't eat.
"Anyone who has ever experienced that could never do away with family welfare payments."
University of Sao Paulo political science professor Rubens Figueireido said the last two weeks of the campaign will be fiercely competitive.
"The big problem faced by Marina is that she has a very weak party coalition, and very limited financial resources compared to the Workers Party," he said.
"She has has a much weaker campaign organization, has had much less time on television and this is the first time that she is experiencing what it is like to be attacked as a candidate, because in 2010 (when she first ran for elective office) she was celebrated everywhere she went, and was not yet seen as a threat."
Nobody saw them running
That murder was committed
Well there ain't no justice in it
