Calls for an Investigation Into Brazil's Ex-Leader Pressure is growing for prosecutors to open an investigation into popular former President Luiz Inacio Lula da Silva amid new accusations he knew about a cash-for-votes in Congress scheme that has seen convictions of 25 people, including his one-time chief of staff. Silva, who left office in 2010 with an 87 percent approval rating and was once called "the most popular politician on Earth" by President Barack Obama, has so far dodged accusations against him. He denies any wrongdoing in what is seen as the biggest corruption case in Brazil's history. But now newspaper editorials, opposition politicians and some average Brazilian voters are saying they want to see the Attorney General's Office order an investigation into allegations made by a top figure in the corruption case that Silva approved of the scheme and used cash from it while in office. "He's such a powerful figure in Brazil - you're telling me all this happened under his nose and he didn't know?" said Debora Barreto, a 30-year-old banker doing some window shopping in central Sao Paulo. It's important this be investigated, there is too much money and power involved. FILE - In this May 16, 2012 file photo, Brazil's former President Luiz Inacio Lula da Silva attends the installation of the Truth Commission at Planalto presidential palace in Brasilia, Brazil. Pressure is growing for prosecutors to open an investigation into popular former President Luiz Inacio Lula da Silva amid new accusations he knew of a cash-for-votes in Congress scheme that has seen 25 people, including his one-time chief of staff, convicted. (AP Photo/Eraldo Peres, File) Close Working in Silva's favor is his popularity - polls indicate he could win if he ran again for the presidency in 2014. And he benefits from the low credibility of his accuser, businessman Marcos Valerio, who has been sentenced to more than 40 years in prison and fined $1.3 million for being what the Supreme Court called the "operator" of the scheme that put cash into the pockets of legislators in return for their support of Silva's policies after he took office in 2003. "What most impresses me is how a person who has been convicted and sentenced ... all of a sudden, and in an act of desperation to lower his sentence, becomes a credible person," said Gilberto Carvalho, secretary to current President Dilma Rousseff, a Silva protege. What this man has revealed concerning former President Lula is impressively false. Any investigation into Silva would need to be opened by federal prosecutors. A spokeswoman for the Attorney General's Office said no statements on the new accusations against Silva would be made until the Supreme Court entirely closes its corruption trial that included 37 defendants, which may happen this week. The scandal is known in Brazil as the "mensalao," or big monthly allowance, for the sums of up to $10,000 handed over to politicians. It came to light in 2005 while Silva was in office. The case has done little to tarnish the reputation enjoyed by Silva, who left office after two 4-year terms on Jan. 1, 2011, with the near-mythical status of Brazil's first working class president whose policies lifted millions out of poverty. Along with Valerio, the Supreme Court last month convicted Silva's once powerful former chief of staff, Jose Dirceu, of racketeering and of leading the vote-buying scheme in Congress. He was sentenced to nearly 11 years in prison. Twenty-two other figures, including politicians, aides, and bankers, were convicted on various charges. Twelve other defendants in the case were absolved of committing any crimes. The new accusations against Silva represent the first time one of the defendants in the landmark corruption trial broke ranks and told prosecutors the former leader was involved. Those accusations, however, were made by Valerio only after he was already found guilty for his own part in the case.