Khalid Abdullah Tariq Al Mansour is also known as Donald Warden, a prominent muslim and black nationalist founder of the California based Afro-American Association (1962). Members of his organization included Black Panther founder Huey Newton, Bobby Seale,and Maulana Karenga (aka Ronald McKinley Everett, Ron Everett) who is the founder of Kwanzaa, a week-long Pan-African celebration observed each year from December 26 to January 1. Warden/Mansour is widely regarded as a mentor of Newton, Seale, et al. Though purely speculative, it is possible that Obama could have met Warden/Mansour when he was a student at Columbia University during one of his lectures.

http://www.google.com/search?hl=en&ie=ISO-8859-1&q=Donald+Warden&btnG=Search

http://lib.berkeley.edu/MRC/pacificapanthers.html

http://lemming.mahost.org/library/seize/seize1.htm

http://books.google.com/books?id=F9Ap_5fNWFsC&pg=PA26&lpg=PA26&dq=Donald+Warden&source=web&ots=TqOWOG3-Z_&sig=N83aSXJm2jK2hp925tcadVDSgTU&hl=en&sa=X&oi=book_result&resnum=10&ct=result