RIO DE JANEIRO — Raquel Dodge, Brazil’s new attorney general, stood on stage during her swearing-in ceremony on Monday, vowing to clamp down on graft and quoting Pope Francis on the corrosive effect of corruption on societies.

At a table only a few feet away sat three men with a big personal stake in how far Ms. Dodge takes her pledge — Brazil’s president, its Senate leader and the head of the nation’s house of representatives.

All three are under investigation in the sprawling corruption case that has upended the political system in Brazil. Now, the entire nation will be watching to see whether Ms. Dodge pushes forward with the judiciary’s crackdown on political corruption, or dials back the pressure in the interest of political stability.

“The corrupt actor is so burrowed and happy to feed his self-sufficiency that he doesn’t let anything or anyone question him,” said Ms. Dodge, quoting from the pope’s views on corruption issued last year. “He has created a self-esteem based on fraudulent attitudes: spends his life in the shortcuts of opportunism, at the expense of his own dignity and that of others.”