Nigerians turned out en masse to vote in a presidential election Saturday that analysts say is too close to call.

Good-humored voters smiled when electoral officials arrived late at many polling stations where registration was to start at 8 a.m. (0700 GMT) followed by voting from 1:30 p.m. (12:30 GMT).

Nearly 60 million voters are registered for the first election in Nigeria's history where an opposition candidate has a realistic chance of defeating a sitting president.

President Goodluck Jonathan and former military dictator Muhammadu Buhari are front-runners among 14 candidates who want to govern Africa's most populous nation beset by a northeastern Islamic uprising.

Buhari, resplendent in white robes, was the first voter to have his fingerprints taken at a polling station that opened a half hour late in Daura, his hometown in northern Katsina state.

He was followed an hour later by Jonathan, in sartorial black with his trademark Fedora hat, in southern oil-rich state of Bayelsa. Jonathan's registration was delayed for half an hour, apparently because a succession of newly imported card readers failed to recognize his fingerprint. Biometric cards and readers are being used for the first time to prevent the kind of fraud that has marred previous votes.

Afterward, Jonathan wiped sweat from his brow and urged people to be patient as he had through his 30-minute wait, telling Channels TV: "I appeal to all Nigerians to be patient no matter the pains it takes as long as if as a nation we can conduct free and fair elections that the whole world will accept."

This is only the eighth election since Nigeria's independence from Britain in 1960. In a country steeped in a history of military coups and bloodshed caused by politics, ethnicity, land disputes, oil theft and, lately, the Boko Haram Islamic uprising, the election is important as the nation with Africa's largest economy consolidates its democracy.

There's a lot of international interest, especially among nervous foreign investors as Nigeria is Africa's largest destination for direct foreign investment. Its oil-dependent economy is hurting from slashed petroleum prices.

Jonathan and Buhari on Thursday signed a peace pledge and promised to accept the results of a free and fair election. But already dozens have been killed in pre-election violence amid hate speech highlighting the religious, ethnic and geographic divisions among Nigerians.

Thousands of Nigerians and foreigners working here have left the country amid fears of post-election violence.

The Islamic uprising that killed an estimated 10,000 people last year has exacerbated relations between Christians like Jonathan, who dominate the southern, oil-rich area of Nigeria, and Muslims like Buhari who are the majority in the agricultural and cattle-herding lands of the north. The population of 170 million is almost evenly divided between Christians and Muslims.

Some 1,000 people were killed in rioting after Buhari lost to Jonathan in the 2011 elections.

Then, there was no doubt that Jonathan had swept the polls by millions of votes.

Now the race is much closer. The game-changer that transformed Nigeria's political landscape came two years ago when the main opposition parties formed a coalition and for the first time united behind one candidate, Buhari.