Brasilia (Brazil) (AFP) - Brazil's Socialist party named popular environmentalist Marina Silva its presidential candidate Wednesday, reshaping the political landscape after her late running mate Eduardo Campos died in a plane crash last week.
Campos's death has radically transformed the outlook for the October vote, possibly setting up Silva, his former vice presidential candidate, to unseat incumbent Dilma Rousseff in a runoff, according to the latest poll.
"I will give the best I have in me," said Silva, a 56-year-old former environment minister, after the announcement.
"Our proposals seek a more just, economically prosperous and socially fair, politically democratic and environmentally sustainable Brazil," added Silva, whose life story is one of astounding personal mobility.
Born into a poor family of rubber tappers in the Amazon, she only learned to read and write at 16 years old, the start of a meteoric rise to become a figurehead of the country's environmental movement.
PSB president Roberto Amaral said party leaders had chosen Silva unanimously to replace Campos at the top of the ticket.
"We had the immense luck to have her as a substitute," he told a press conference.
Socialist lawmaker Beto Albuquerque was named the party's new vice presidential candidate.
The PSB had been widely expected to name Silva as its new candidate after Campos, a 49-year-old former governor, was killed when his campaign jet crashed en route to Sao Paulo.
Before Campos's death, the election outlook had been stable for months, with Rousseff polling about 36 percent, Neves 20 percent and Campos eight percent.
But Silva's entry into the race could prove a real threat for Rousseff, who is seeking a second four-year term.
On Monday, polling firm Datafolha put Silva in second place ahead of the October 5 first-round vote, with 21 percent support against 36 percent for Rousseff and 20 percent for Social Democrat Aecio Neves.
And it found she would beat Rousseff in an October 26 runoff, 47 percent to 43 percent.
The poll was the first taken since Campos's death in the August 13 plane crash.
- Battle for swing votes -
Silva has been considered a top presidential contender ever since surprising many pundits in the 2010 election by coming in third with 19 percent of the vote running on the tiny Green Party's ticket.
But Brazil's electoral court ruled last October that she had failed to collect enough signatures to register her new party, Sustainability Network, in time for this year's race.
She then opted to join forces with the affable, politically connected Campos and the PSB.
With her compelling personal story and broad-based appeal, she could be even more effective than her late running mate at selling the party's message of change after 20 years of government by Rousseff's Workers' Party (PT) and Neves's PSDB.
And an evangelical Christian, she appeals to both religious conservatives and the left.
Rousseff for her part can count on a rock-solid base but could struggle to capture swing votes, said Datafolha's director Mauro Paulino.
Her "Workers' Party has a captive vote of 30 percent, a third of the electorate that always votes for its candidate," he told AFP.
But another third of the electorate is looking for an alternative, and that is the niche that Silva and Neves will vie for, he said.
Rousseff, 66, was Brazil's first woman president. She has struggled to kickstart the Brazilian economy, the largest in Latin America and seventh largest in the world.
After eight years of rapid growth under her popular predecessor and mentor, Luiz Inacio Lula da Silva -- hitting 7.5 percent in 2010 -- the economy has been sluggish under Rousseff, registering an average 2.1-percent growth from 2011 to 2013.