Senator Saxby Chambliss, a Georgia Republican who is the committee’s vice chairman, signaled Congressional opposition to the plan, which administration officials have said would not release the prisoners outright but transfer them to authorities in Qatar, where the Taliban are setting up an office to hold political talks. “We should not transfer these detainees from Guantánamo,” Mr. Chambliss said, citing American intelligence assessments warning of the risks the prisoners posed.

Mr. Clapper acknowledged that the Taliban remained “a resilient, determined adversary” and underscored that any deal involving prisoners would hinge on “where these detainees might go and the conditions in which they would be controlled or surveilled.”

As Taliban leaders debate whether to fight or cut a deal, the death of Bin Laden has severely weakened a Qaeda leadership that was already reeling from the death or capture of several other top leaders. The losses have forced the organization to rely more heavily on affiliates in such places as North Africa, Iraq and Yemen, as well as individual “lone wolf” extremists in the United States.

Intelligence officials say that continued pressure by the United States and its allies — including drone strikes, efforts to dry up terrorists’ financing and campaigns to counter extremist recruiting propaganda — are likely to fragment this already decentralized movement.

“As long as we sustain the pressure on it, we judge that core Al Qaeda will be of largely symbolic importance to the global jihadist movement,” Mr. Clapper said in his opening statement.

Of all the affiliates that have sprouted up over the past decade, intelligence analysts say that the Qaeda arm in Yemen, Al Qaeda in the Arabian Peninsula, poses the greatest immediate threat to the United States. Mr. Clapper said that the death last September of Anwar al-Awlaki, an American-born cleric who was a top propagandist and operational planner for the Yemen affiliate, “probably reduces, at least temporarily, A.Q.A.P.’s ability to plan transnational attacks.”

Over all, Al Qaeda has struggled to keep pace with events unfolding as result of the Arab Spring, Mr. Clapper said, warning, however, that “prolonged instability or unmet promises of reform would give Al Qaeda, its affiliates and its allies more time to establish networks, gain support and potentially engage in operations, probably with less scrutiny from local security services.”