David is a professor of public service and was the founding director of the Center for Public Leadership at the Harvard Kennedy School. In addition, he serves as a senior political analyst for CNN and works actively with a rising generation of new leaders. In the past, he has served as a White House adviser to four U.S. presidents of both parties: Nixon, Ford, Reagan and Clinton. He wrote about those experiences in his New York Times best-seller, Eyewitness to Power: The Essence of Leadership, Nixon to Clinton (Simon & Schuster, 2001).