The turnaround comes as Nigerians prepare for Feb. 14 presidential elections that are expected to be the most closely contested since decades of military dictatorship ended in 1999. President Goodluck Jonathan, 57, is being challenged by former military dictator Gen. Muhammadu Buhari, 72. Buhari is being touted by an opposition coalition as more likely to succeed in curbing the insurgency and in fighting corruption that Jonathan is accused of fueling.