"We all will make mistakes. The key is to recognize them and admit them, to learn from them, and to take off the rear-view mirrors -- drive on and avoid making them again," he said.
The departure of Petraeus will add another hole to Obama's leadership team, which is expected to lose some high-profile faces in the coming weeks and months. Secretary of State Hillary Clinton is among the cabinet members who have said they will not stay in the administration for a second term. A hole at CIA will add yet another position that requires Senate confirmation to that list.