And Mutuassim, a national security adviser who also commands his own militia, has been considered a rival to Seif in the competition to succeed their father. But Saadi, who has drifted through careers as a professional soccer player, a military officer and a businessman, firmly backs the plan, an associate said.

The two sons “want to move toward change for the country” without their father, one person close to the Seif and Saadi camp said Sunday, speaking on condition of anonymity for fear of retribution. “They have hit so many brick walls with the old guard, and if they have the go-ahead, they will bring the country up quickly.” One son, this person said, has said many times that “the wishes of the rebellion were his own.”

The proposals are the latest turn in a drama between Seif and his father that has played out for years on the stage of Libyan public life as the son has alternately pushed forward with calls for political reforms and then pulled back. During the recent revolt, he appeared to march in lockstep with his father in vowing to stamp out the rebels. “We are coming,” he declared to a crowd of supporters who chanted, “Seif al-Islam, step on the rats.”

The proposals are also the latest sign that the Qaddafi government may be feeling the pressure from two weeks of allied airstrikes that have severely diminished the advantage in equipment of the Qaddafi militias. A senior Libyan official arrived in Athens for talks about a potential resolution to the conflict, the Reuters news service reported. And Mohamed Ismail, a top aide to Seif, is returning from a trip to London, where, a Libyan official said, he presented the proposal for Seif to take over from his father.