Story highlights Critics: Luiz Inacio Lula da Silva is trying to protect himself from possible imprisonment

Former Brazilian leader agrees to become presidential chief of staff

The two-time president is facing investigations into money laundering

Rio de Janeiro (CNN) Former Brazilian President Luiz Inacio Lula da Silva has accepted an offer to become chief of staff for his successor and protégé, Dilma Rousseff, giving him some legal immunity in a corruption investigation and fueling political tensions in the divided country.

At a news conference, Rousseff praised the two-time president, known popularly as "Lula," for stepping up to the plate to help her embattled government.

"He comes with his knowledge of the country, of the needs of the country and his commitment ... it is going to be a huge boost for my government," she said.

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Supporters hope Lula da Silva will help shore up support among party faithful despite a prolonged recession and rock-bottom approval rating for Rousseff.

"He comes with his political capital; he's a great communicator," Rousseff said. "He makes me very comfortable"

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