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.
The timing of the accusations led Silva and his supporters, including Rousseff, to label as "lies" the testimony Valerio offered to federal prosecutors in September and which was first reported this week by the newspaper Estado de S. Paulo after it obtained a copy of the testimony.
Alexandre Barros, with the Early Warning political risk group in Brasilia, said the impact of the latest accusations "will be very small and of short duration" because Silva's accuser Valerio "has been the big bandit with no credibility whatsoever."
"It is all a matter of Valerio's credibility versus Lula's credibility, and Lula comes out ahead," Barros said, using the nickname Silva is universally known by. "For the average supporter of Lula — the Brazilian equivalent of Joe six pack in the United States — this whole thing means little if anything at all. Lula will come out of all this unscathed."
But the charges have led many in Brazil's aggressive press to call for a prompt investigation.
"The latest accusations could be summed up as the desperation of a condemned man," the newspaper Folha de S. Paulo said in a Wednesday editorial. "There is no doubt, however, that they should be investigated with the utmost attention."
For political columnist Merval Pereira, popularity should not shield Silva from an investigation.
"It's dangerous for a democracy, this thesis that one cannot speak of Lula. Anything that's said of him turns into a coup attempt to demoralize the steelworker who came to power to help his people," Pereira wrote. "What's not possible is to assume that Lula is untouchable and shielded forever."
Associated Press writer Stan Lehman contributed to this report.