* Critics say Rousseff's green platform is hollow
* Campaign has largely been void of green issues
By Raymond Colitt
BRASILIA, Oct 20 (Reuters) - Brazil's ruling party candidate sought on Wednesday to win over green swing voters ahead of an Oct. 31 presidential runoff, pledging to slash Amazon deforestation and greenhouse gas emissions.
Dilma Rousseff and her main rival Jose Serra are both courting supporters of former environment minister Marina Silva of the Green Party, who placed a strong third with 19 percent of the votes in a first round vote on Oct. 3.
Polls show that former Sao Paulo state governor Serra is capturing far more Silva votes than Rousseff. But he still trails the frontrunner by between 4-12 percentage points in polls.
"My pledge is to reduce deforestation in the Amazon by 80 percent," Rousseff told a crowd of supporters mostly from her Workers' Party.
Referring to a 2020 target she and President Luiz Inacio Lula da Silva announced at global climate talks in Copenhagen last year, Rousseff said she would also reduce greenhouse gas emissions by around 39 percent. [ID:nN15201599]
"I will keep those promises," Rousseff said as she presented her environmental platform in the capital Brasilia.
Full coverage of election: [ID:nBRAZIL]
Election Top News page: link.reuters.com/dux43p
Graphic on opinion polls: r.reuters.com/vet88p
Special report on Rousseff: link.reuters.com/fab25p
Political risks in Brazil: [ID:nRISKBR]
On Sunday, the Green Party voted against endorsing a candidate in the runoff, a decision widely viewed as a setback for Serra. [ID:nN1796674]
Several environmental celebrities, Green Party leaders, and native Indians in feathered headdress on Wednesday showcased their support for Rousseff, Lula's former chief of staff.
"I was for Marina in the first round and now I'm for Dilma," said Angela Mendes, the daughter of legendary conservationist Chico Mendes.
Critics said the event generated few concrete proposals.
"This means nothing. It's vague enough for her to dance around once she's in office," said Sergio Leitao, a Greenpeace campaign director.
Greenpeace protesters demanding that Rousseff adopt a zero deforestation target briefly interrupted the event. Rousseff said the protesters were entitled to their democratic rights but that she would not be pressured.
"I don't hold political auctions to win support," Rousseff said.
Much of her 13-point platform focused on advancing existing policies and most were vague. One proposal called for the "strengthening of environmental education." (Editing by Xavier Briand)