Nigeria Votes in Sharply Contested Presidential Election

KANO, Nigeria — The most sharply contested election in Nigeria’s post-independence history wound down to a tense conclusion on Saturday amid fears that a polarized electorate would clash regardless of the outcome in a country split on religious, ethnic and sectional lines.

There appeared to be little middle ground between partisans of the incumbent president, Goodluck Jonathan, a Christian from the south hated in the north for mismanaging a bloody Islamist insurgency at steep cost, and his challenger, Muhammadu Buhari, a former military ruler, a northerner and a belated democratic convert whose Muslim faith and authoritarian past are feared in the south.

Voters on Saturday morning crowded around registration stations here in the north’s largest city, a packed metropolis of more than five million, as hitches in the process added to the tension. Election officials were more than two hours late in some places, and malfunctioning electronic registration machines — a new system designed to limit endemic fraud — stymied voters in others.

In the crowds partisan anger seethed in Kano, hard-hit by Boko Haram bombings and suicide attacks, with hints that — as in previous Nigeria elections — the contest may not end when results are announced early next week. Nearly 1,000 people were killed after the 2011 vote, dozens of them here in Kano, in an election nonetheless judged to have been one of Nigeria’s most peaceful.

This year the stakes are far higher as the governing party’s hold on power is threatened for the first time since the end of military rule in 1999. Analysts reckoned that the contest was too close to call, though the momentum may have shifted slightly to Mr. Jonathan after his military chiefs forced a six-week delay in the voting, which was originally scheduled for February. Mr. Buhari’s supporters, on the other hand, have spoken of declaring a parallel government if they judge the vote to have been rigged, or of taking their grievances to the streets.

“I’m apprehensive,” said Clement Nwankwo, who heads a leading political study group in Nigeria’s capital, Abuja. “I’ve just seen so much desperation on all sides. People have dug in, and I don’t see that anybody is willing to compromise.”

In Kano’s dirt-street, trash-encrusted Fagge district, many in the packed crowd warned against a declaration of victory by the incumbent, Mr. Jonathan.

“We will not accept it,” said Mannir Bala, 32, a trader. “We are only interested in Buhari.” Others shouted their agreement. “We won’t allow Jonathan this time,” Mr. Bala said. Others chimed in with complaints that echoed official statistics showing an increase in poverty in Nigeria in recent years: their district had no electricity, one man shouted; no water, another said; no education, said a third.

Other would-be voters here brandished their new plastic identification cards and spoke of wanting change after years of Islamist violence, corruption scandals and stagnant living standards. “There is hardship in this country. No good security,” said Dayyabu Yahaya Inuwa, a civil servant, waiting to register in the shadow of the ocher-colored walls of the emir of Kano’s palace in this centuries-old center of Islamic culture. The crowd had been waiting over two hours to register but still no election officials had appeared. “By the grace of Allah we will change the government,” Mr. Inuwa said.

In the background to this year’s vote has hovered Boko Haram, whose violent insurgency is now stretching into its sixth year. The tide appears to have turned in the fight against the Islamists in the immediate period before the election — particularly during the six-week delay demanded by the country’s military chiefs — after years of halfhearted engagement by the Nigerian military. South African mercenaries hired by the government have made a substantial difference, officials in the north, diplomats and analysts said, along with a regional military push by Chad, Cameroon and Niger and the Nigerians themselves — though the other countries complain there is little to no coordination with the Nigerians.

The country’s airwaves and newspapers have been filled with advertising by the government trumpeting the success of its belated campaign against Boko Haram, and nearly every day the military announces a new success, after years of defeats. Friday — on the eve of the election — Nigerian army officials said they had overrun the Boko Haram stronghold of Gwoza.

Analysts said there was little doubt that the six-week delay had benefited the governing party, the People’s Democratic Party. “The P.D.P. has got a swagger that they did not have before,” said Darren Kew, a Nigeria expert at the University of Massachusetts Boston, who is observing the election here.