ABUJA (Reuters) - Tens of millions of Nigerians voted on Saturday in the most credible presidential election for decades, with early results pointing to a close race between President Goodluck Jonathan and rival Muhammadu Buhari.
From the tin-roofed shacks of the Niger Delta, where Jonathan cast his vote, to the dusty alleyways of Daura, the northern home village of ex-military ruler Buhari, voters came out en masse.
"The politicians should know if they don't perform they are going to be voted out," said businessman Ahibuogwu Brian among the populous lagoon-side shanties of Makoko in the sprawling commercial hub of Lagos. "The electorate now know we have the power to chose our leaders."
The polls pit front-runner Jonathan, the first head of state from the oil-producing Niger Delta, against Buhari, a northern Muslim with a reputation as a disciplinarian.
Early results showed Jonathan had done well in much of predominantly Christian southern Nigeria, including areas such as Lagos where his ruling party had struggled in a parliamentary election a week ago.
But first results from heavily Muslim northern states showed Buhari with a wide lead and a very high turnout which could help counterbalance his lack of support in the south.
"Across the country it will be close," said former government minister Nasir el-Rufai, a Buhari supporter, at a vote counting center in Abuja.
"My only fear is it will become a north-south issue if we see a situation where Buhari sweeps the north and Jonathan does well in the south. We may have to go to a run-off," he told Reuters.
To win in the first round, a candidate needs a simple majority and a quarter of the vote in two thirds of the 36 states.
There are more than 73 million registered voters and 120,000 polling stations. Final results could take days.
Election workers, party officials, observers and armed police crammed into a classroom of an Abuja school to try to collate results from 35 polling units. Heated arguments flared and dissipated, but observers said the system was working.
"What we see appears to be logical and there is care being taken that what was counted out there is reflected in here," said former Canadian Prime Minister Joe Clark.
Across most of the country of 150 million there was little sign of the chaos and violence that has dogged past elections although two bombs panicked voters in the troubled northeastern city of Maiduguri.
There were reports of underage voting and attempts at ballot-stuffing in some areas. In the northern state of Bauchi irate youths torched an electoral commission office after officials were allegedly found thumbprinting ballot papers.
"There are concerns that need to be addressed, but overall this is much better than the past," said Clement Nwankwo, head of the Policy and Legal Advocacy Center (PLAC) in Abuja, working with more than 20 civil society groups to monitor the vote.
President Jonathan, a former zoology teacher born to a family of canoe makers, is the favorite. He is backed by the national machinery of the People's Democratic Party (PDP), whose candidate has won every presidential race since 1999.
"For economic reasons and to reduce tension, we pray that whoever will win should win at the first ballot," Jonathan said after casting his vote in the Niger Delta.
But Jonathan is resented by some in the north, who believe he is usurping the right of a northerner to the presidency for another four years. He inherited office after his predecessor, northerner Umaru Yar'Adua, died last year in his first term, interrupting a rotation between north and south.
Buhari, a strict Muslim known for his "War Against Indiscipline," is hoping to capitalize on some of the resentment despite his Congress for Progressive Change (CPC) being a young party.
The former general told Reuters he feared the ruling party was trying to manipulate the vote out of desperation.
"They could do anything and they are trying everything but luckily people are very sensitive this time around and they are determined to make their vote count," he said.
Fellow opposition contender Nuhu Ribadu's Action Congress of Nigeria (ACN) party has its stronghold in the southwest, and could help force a run-off. But the two failed to agree a last minute alliance this week, leaving the anti-Jonathan vote split.