ABUJA- Nigerian opposition leader Muhammadu Buhari built a lead of 2 million votes with three-quarters of states counted on Monday, raising the prospect of a stunning ballot box victory for a man who first came to power three decades ago via a military coup. According to results collated by Reuters, Buhari had notched up 12 million votes. A 72-year-old general, he has campaigned as a born-again democrat intent on cleaning up the corrupt politics of Africa's most populous nation. This compared to 10 million for President Goodluck Jonathan, a one-time zoology professor whose five years at the helm of the continent's biggest economy and top oil producer have been plagued by corruption scandals and a bloody insurgency by Islamist Boko Haram militants. There is still time for a reversal of fortunes, with some of Jonathan's big support bases in the oil-producing Niger Delta yet to report.