MASAYA, Nicaragua — The revolutionary, many Nicaraguans say, is suddenly facing a revolution of his own.

The insurrection that led to the rise of President Daniel Ortega and his Cold War struggles with the United States began here in Masaya 40 years ago. Mr. Ortega’s brother died fighting in this town, and an old national guard post still stands as a landmark to the uprising that brought their leftist guerrilla movement to power.

But in recent days, the guard post has been turned into a charred, vandalized mess. Protesters have even taken a famous war slogan and spray-painted it on the walls in a mocking warning to Mr. Ortega.

“Let your momma surrender,” it says.

Nicaragua is undergoing its biggest uprising since the civil war ended in 1990.