By Anthony Boadle and Lisandra Paraguassu
BRASILIA (Reuters) - Unprecedented graft probes have scorched Brazil's political landscape and created the opening for a clean outsider to win the presidential election this October, environmentalist and candidate to the highest office Marina Silva said in a Wednesday interview.
Though she has been in politics for 30 years and spent most of that time with the once-mighty Workers' Party, Silva has denounced Brazil's traditional parties for leaning on vast kickback schemes to keep office. She started her own party from scratch four years ago.
"I am not ashamed to be a politician. I am a political person, but completely outside the criminal structures that took over Brazilian politics," Silva told Reuters at the headquarters of her Sustainability Network party, or REDE.
Silva is counting on public outrage at Brazil's political class to help propel her to the presidency. The former senator has made two prior presidential bids, winning about 20 percent of votes in 2010 and 2014. Neither was sufficient to enable her to reach a second round run-off.
Silva's chances will be much improved this time around if the potential frontrunner, the still popular former President Luiz Inacio Lula da Silva, is barred from running due to a corruption conviction. The two candidates are not related.
Absent Lula, a recent Datafolha opinion poll indicated that right-wing candidate Jair Bolsonaro would win the first-round vote and Silva would come second. Silva would likely triumph in a second-round runoff, the poll suggested.
That poll showed 35 percent of Lula's supporters would vote for no one if he cannot run, while Silva would draw 15 percent of his voters, the most of any candidate in the poll.
The 59-year-old Silva was born into poverty, the daughter of rubber tappers in the Amazon rainforest. She learnt to read at age 16 after overcoming childhood malaria and mercury poisoning.
She first gained fame as a rainforest activist, kicking off a political career that made her the first environment minister under Lula.
Now Brazil's four main political parties, including Lula's Workers' Party, had lost sight of the nation's interests and only wanted to cling to power by any means, Silva said.
If elected, Silva said she would strengthen anti-corruption investigations and move to end some legal protections from prosecution that sitting politicians enjoy.
With only a handful of lawmakers in her party at present, Silva said she was in talks with other parties on possible electoral alliances. Still, she said she would not forfeit her ideas to gain more electoral clout.
She said her main aim was to stop the destruction of the Amazon rainforest, and that she was also committed to fiscal responsibility. She would limit increases in public spending to the rate of economic growth, she added.
Silva is keen to keep state-run companies such as Petroleo Brasileiro SA in public hands, and criticized President Michel Temer's plan to privatise Eletrobras, Brazil's largest power utility.
She said Temer's concessions to pressure groups had limited his pension bill and that reducing a budget deficit looked set to fall to the next government.
(Reporting by Anthony Boadle and Lisandra Paraguassu, Editing by Rosalba O'Brien)