MANAGUA, Nicaragua — President Daniel Ortega of Nicaragua announced on Sunday that he was reversing a social security overhaul that had prompted days of protests in which up to two dozen people died.

“We have to re-establish order,” Mr. Ortega said in televised remarks. “We cannot allow groups to impose chaos, crime and looting.”

His announcement seemed to acknowledge that the protests, which started on Wednesday as a picket by college students against the social security overhaul, had become a serious challenge to his authority.

But it is unlikely to sway protesters who still have other grievances against his government — including Mr. Ortega’s interference with the National Assembly, the law and the Constitution, like eliminating term limits. He is also widely criticized for having manipulated the Supreme Court, the elections council and mayoral races.