Opposition candidate Muhammadu Buhari is close to a stunning victory over Nigerian President Goodluck Jonathan, with just a few areas left to declare.
Gen Buhari, a former military ruler, is ahead by almost three million votes, with results still to come from just five states.
Analysts say it is hard to see how Mr Jonathan can overcome this lead.
The opposition has never won a presidential election in Nigeria, Africa’s most populous state.
Observers have generally praised the election but there have been allegations of fraud, which could lead to protests and violence.
More than 800 people were killed in protests after Mr Jonathan beat Gen Buhari in the previous election.