Former Sen. Sam Nunn, the pre-eminent Democratic voice on national security and national defense, just endorsed Sen. Barack ObamaBarack Hussein ObamaBiden's chief aide says president wants teams, no rivals Where is the campus debate on immigration? Gerald Ford Foundation urges 'dignified' presidential transition MORE (D-Ill.).

Former Sen. David Boren and former Labor Secretary Robert Reich did as well.

The Nunn endorsement is a very, very, very big deal. Not only does it give Obama national security backing, but Nunn is enormously respected by superdelegates.

Expect more announcements soon.