ROME — When Virginia Raggi, Rome’s first female mayor, was elected in June, she represented the anti-establishment Five Star Movement’s highest aspiration — to show Italy how nonprofessional politicians could turn things around.

Yet three months later, the Five Star Movement’s shining moment has become a mess, and Ms. Raggi, 38, a lawyer with almost no political experience who ran as a clean-hands reformer, appears to be floundering.

Garbage piled up in the streets through the summer. Five important officials have resigned, some tainted by investigations for malfeasance. By this month, things were so bad that the comedian Beppe Grillo, a founder of the movement, reversed a vow to stay out of politics and stepped in to shore up Ms. Raggi amid speculation about an early resignation.

On Monday, one of Italy’s leading newspapers, La Repubblica, published excerpts from a letter to Ms. Raggi, signed by about 70 City Hall managers in Rome, that lamented administrative paralysis and a lack of guidance. Residents, too, seem to be at the end of their ropes.