PARIS — After weeks of large street protests, Algeria’s army chief of staff called Tuesday for a declaration that the incapacitated 82-year-old president, Abdelaziz Bouteflika, be deemed unfit to rule, appearing to pave the way for an end to his 20 years in power.

The army chief of staff, Gen. Ahmed Gaid Salah, one of the top power brokers in the regime, who had until recently been loyal to the president, threw his weight behind what he called the “legitimate demands” of the demonstrators in a speech broadcast continuously on Algerian television.

The statement from the powerful army leader, in a speech in the central town of Ouargla, seemed to signal an end to the president’s rule, and the thousands who have taken to the streets of the capital Algiers and other cities nearly daily for weeks greeted the news with joy. Mr. Bouteflika, paralyzed and in a wheelchair, has not spoken to his country in years.