WASHINGTON — John Brennan won Senate confirmation Thursday to head the CIA after a late struggle that had more to do with presidential power to order drone strikes than with his credentials to lead the spy agency.

The vote was 63-34. Brennan will replace Mike Morrell, the acting CIA director since November.

The vote came after the Obama administration bowed to demands from Republican Sen. Rand Paul of Kentucky and specified limits on the president’s authority to order drone strikes against American citizens in the United States.

Paul declared he was satisfied with the administration’s statement, which said the president does not have the authority to use a drone to kill an American not engaged in combat on American soil.