** FILE ** Opposition presidential candidate, and former military ruler of Nigeria from 1984 to 1985, Muhammadu Buhari speaks at the Nigeria Labor Congress in Abuja in this Wednesday, April 16, 2003 file photo. The former military ruler won the presidential ticket of Nigeria's largest opposition party after six rivals withdrew from the race. All six challengers pulled out just before voting started late Monday Dec 18 2006. (AP Photo/Ben Curtis, File)