SAO PAULO (AP) — A Brazilian appeals court on Friday slapped down a second attempt to block a Cabinet post for former President Luiz Inacio Lula da Silva and supporters rallied to back an embattled government facing a host of crises.

Silva was sworn in as chief aide to President Dilma Rousseff on Thursday, a post that will let the charismatic politician help the president battle an impeachment effort and one that also makes it harder to investigate any possible links to a corruption scandal at the state oil company.

Opponents quickly won injunctions from two regional federal judges to block his appointment, but both were quickly overturned.

Supporters of Silva, who was one of the world's most famous leaders as president from 2003 to 2010, began to gather for rallies in a handful of cities across Brazil, particularly in the industrial south, where the former factory worker has his base.

The political turmoil comes as Brazil prepares to host the Summer Olympics in August and Latin America's most populous nation faces crises on several fronts. The country is at the center of an outbreak of the Zika virus, which health experts believe can cause abnormally small heads in newborns. And its economy, long an engine for neighboring countries, has sharply contracted by nearly 4 percent. Inflation has spiked the last year and announcements of job layoffs have become common.

Rousseff's opponents accuse her of trying to help Silva avoid legal woes. Less than two weeks ago, he was taken in for questioning in the sprawling Petrobras kickback probe that has ensnared both allies and rivals of the former president. Cabinet members cannot be investigated, charged or imprisoned unless authorized by the Supreme Court.

Rousseff supporters have a different take: They say the 70-year-old Silva, known for his ability to build consensus and disarming charisma, could save Rousseff's job and help bring the economy back from the abyss.

Rousseff, with approval ratings in the single digits, is fighting against attempts to oust her over allegations of fiscal mismanagement unrelated to the Petrobras case. The move toward impeachment advanced this week as the lower house established a special commission on the matter.

Both Rousseff and Lula have repeatedly denied any wrongdoing.

In a public letter Friday, Silva called the last two weeks "sad and embarrassing episodes" that hurt all Brazilians.

As he often does, he harkened to his hardscrabble past. He noted he had little formal education, "But I know, as a human being, how to distinguish between right and wrong, and what is justice and injustice."

He also questioned the legality of the surprise release of tapped phone calls between him and a host of prominent public figures, including Rousseff herself.

Judge Sergio Moro, overseeing the Petrobras case, released the recordings late Wednesday, hours after the announcement of Silva's appointment, saying that the taps appeared to suggest attempts to influence judicial officials in Lula's favor.

Rousseff called the recordings illegal and said their release made "clear the attempt to overstep the limits of the democratic state."

The simmering anger that bought an estimated 3 million people onto the streets in nationwide anti-government demonstrations over the weekend again spilled over Thursday with protests in Brasilia and Sao Paulo.