* Prominent environmentalist Silva could shake up election
* Silva could steal votes from Lula’s handpicked candidate
* Silva seen attracting women, middle-class voters
By Carmen Munari
SAO PAULO, Aug 10 (Reuters) - A possible presidential run by a former Brazilian environment minister and famed Amazon defender promises to add spice to next year’s election and could be a blow to President Luiz Inacio Lula da Silva’s chances of getting his hand-picked successor elected.
Despite steering Brazil to economic prosperity and maintaining approval ratings above 80 percent, Lula faces a struggle to persuade voters to elect his relatively unknown chief of staff, Dilma Rousseff, in the October 2010 elections.
That task would likely become harder if his former environment minister, Marina Silva, decides to leave the ruling Workers’ Party (PT) and run for the top job as the Green Party candidate, a move she said last week she was considering.
Silva, an iconic figure for environmentalists who rose to the national stage from a poor rubber-tapper family in the Amazon forest, would likely attract left-wing middle-class voters concerned about the environment as well as women voters who might otherwise choose Rousseff, political analysts said.
"She is clearly a figure with a positive image, a respectable biography, and has appeal in the same sectors of the left as Dilma," said Fabio Wanderley Reis, a social sciences professor at the Federal University of Minas Gerais.
The 51-year-old Silva returned to the Senate for the Workers’ Party last year after resigning from the environment portfolio, where she had become increasingly isolated inside Lula’s team and struggled to advance her conservation agenda.
A Green Party poll found that, depending on which candidates run, she would get between 10 and 28 percent of the vote. That compares to 23.5 percent for Rousseff in a survey released by polling firm Sensus in June, which showed just over 40 percent support for Sao Paulo state Governor Jose Serra of the centrist opposition Brazilian Social Democracy Party.
Lula is constitutionally barred from running for a third straight term.
"She has a profile closer to the Workers’ Party voter," said Ricardo Berzoini, the president of the center-left ruling party. "I don’t doubt that it could have this effect (of taking votes from Rousseff)."
DECISION EXPECTED SOON
Ciro Gomes, a deputy in the lower house of Congress for the Brazilian Socialist Party who is also weighing a presidential run, said in an interview with Valor Economico newspaper on Monday that Silva’s bid would "implode" Rousseff’s candidacy.
But one experienced electoral analyst said that the Green Party’s polling numbers for Silva seemed too high and that she may not take significant votes from Rousseff.
"I think it’s best to wait for other polls," said Marcos Coimbra, director of the Vox Populi polling firm.
He said Rousseff would have the substantial benefit of support from Lula, who is promoting her as the "mother" of the government’s huge infrastructure and housing program, a platform that Silva lacks.
Rousseff, 61, cut her political teeth as a militant opposed to Brazil’s military dictatorship in the 1960s and is known as an efficient administrator. But she has never been elected to a major public post and is seen as lacking the charisma and common touch that is Lula’s trademark.
Alfredo Sirkis, the vice-president of the Green Party, said he believed Silva could also steal votes from Serra, who lost to Lula in the 2002 election.
"She will take votes from the minister (Rousseff) because she is a woman and from the PT, and from Serra from the middle class who vote for him despite not liking him," he said.
Silva returned to her remote home state of Acre in northwestern Brazil at the weekend to consider her decision and talk to local politicians. Officials from the PT and the Green Party said she was likely to announce a decision soon, and by the end of August at the latest.
"I‘m not working with the theory that she will leave. With 30 years in the PT, she should stay where there is space to debate sustainable development," said Leonardo Brito, the Workers’ Party president in Acre.
But Silva, who worked closely in Acre with legendary rubber tapper and environmental activist Chico Mendes until his assassination in 1988, was left frustrated after five years as environment minister.
She finally quit in May 2008 after Lula, who has generally favored development over conservation, rebuffed her and named another minister to oversee a government development plan in the Amazon.
(Writing by Stuart Grudgings; Editing by Todd Benson and Patrick Rucker)