Nigerian voters are deciding whether to keep their accidental president in power, though unease among the country's Muslims about the Christian leader could force a runoff in the oil-rich country where elections have long been marred by fraud and violence.
Following bombings in the country's north-east during last week's legislative elections, another blast went off this morning in a residential neighbourhood of Maiduguri, though no injuries were reported.
Assailants also shot the rear windshield of an election official's vehicle in the same town last night, authorities said.
"This election is very important," said Hamza Mohammed, 50, who serves as a local market chairman in the northern town of Katsina. "We want it to be conducted peacefully and we want peace to reign."
Voters must choose whether president Goodluck Jonathan should now be elected after taking over last year when his predecessor Umaru Yar'Adua died in office following a lengthy illness.
Mr Jonathan is the candidate for Nigeria's long-dominant ruling party and is the clear front-runner, but several other candidates threaten to siphon off enough votes that it could go to a second round for the first time since Nigeria became a democracy 12 years ago.
The opposition candidates are capitalising on discontent with the ruling People's Democratic Party. While voters were careful not to mention it by name, they blamed current leaders for a lack of clean drinking water, schools, electricity and jobs in this country where most live on less than two dollars a day.
Among those looking to take away key votes from Mr Jonathan in northern Muslim constituencies is a hometown candidate - former military ruler Muhammadu Buhari. He ruled Nigeria shortly after a 1983 New Year's Eve coup, executing drug dealers and going after corrupt officials while also stifling freedom of speech and jailing journalists.
Former anti-corruption tzar Nuhu Ribadu is also running.