Nigeria’s President Goodluck Jonathan (L) and opposition candidate Gen. Muhammadu Buhari, (R) pose after signing a renewal of their pledge to hold peaceful “free, fair, and credible” elections, at a hotel in the capital Abuja, Nigeria Thursday, March 26, 2015.Nigeria’s President Goodluck Jonathan (L) and opposition candidate Gen. Muhammadu Buhari, (R) listen as Abdulsalami Abubakar former President of Nigeria speaks after signing a renewal of their pledge to hold peaceful “free, fair, and credible” elections, in the capital Abuja, Nigeria on March 26, 2015.Nigeria’s President Goodluck Jonathan (L) and opposition candidate Gen. Muhammadu Buhari, (R) pose after signing a renewal of their pledge to hold peaceful “free, fair, and credible” elections, in the capital Abuja, Nigeria Thursday, March 26, 2015.: Nigerias presidential candidate Gen. Muhammadu Buhari (R) and chairman of the All Progressives Congress (APC) John Odigie (L) hold a press conference after signing a renewal pledge to hold peaceful “free, fair, and credible” elections, in the capital Abuja, Nigeria Thursday, March 26, 2015.