Nigeria held elections Saturday that, if successful would mark the first handover of power from one elected leader to another since Nigerian independence 47 years ago.
But the run-up to the election, and the voting itself, was chaotic. A leading opposition candidate was first barred from running, and then allowed to go forward after the ballots had been distributed.
To win the election, one of the 25 candidates for president must gain the most votes nationwide and at least a quarter of ballots cast in 24 of Nigeria's 36 states. If not, a runoff election would be held within one month.
Nigeria's 61 million registered voters were also voting for 300 seats in the federal legislature. A new government will take power May 29.
Results for the election could be available as early Monday.