He spoke with early results about to start trickling in.It was unclear when a winner would be declared but the vote pitting President Muhammadu Buhari against businessman and ex-vice president Atiku Abubakar was expected to be Nigeria’s tightest since the end of military rule in 1999.

Buhari, 76, is a former military ruler seeking a second term on an anti-corruption platform, while Atiku, 72, has pledged above all to expand the role of the private sector. The outcome appeared to hinge on which man voters trusted most to revamp an economy still struggling from a 2016 recession.

At stake is the leadership of Africa’s top oil producer and biggest economy where a decade-long battle with Islamist militants concentrated in the northeast has made Nigeria pivotal to regional stability.

A credible and relatively calm vote would open a new chapter in the chequered political history of Nigeria, where nearly six decades of independence have been tarnished by military coups, endemic corruption and secessionist movements.

The election was postponed on Feb. 16 just hours before it was due to begin, with authorities citing problems in delivering ballot papers and results sheets in some parts of the country.

“It is highly probable that such a late postponement had negative effects on voter turnout,” John Tomaszewski of the joint U.S. National Democratic Institute and International Republican Institute observers delegation, told reporters.

DELAY “UNDERMINED PUBLIC CONFIDENCE”

“More significantly, the delay also undermined public confidence in INEC,” he said, referring to the Independent National Electoral Commission. It was not immediately clear how lower turnout or the abrupt delay might affect the chances of either main candidate or the credibility of the result.

Situation Room, another monitoring mission comprising over 70 civil society groups, said on Sunday as many as 39 people had been killed in election-related violence, and over 260 in all since the start of the campaign in October.

The election, however, took place “in a generally peaceful environment”, said Hailemariam Desalegn, head of the African Union observer mission and a former premier of Ethiopia.

“There were scattered incidents of violence but it was not seen as pervasive on Election Day,” said Derek Mitchell, president of the U.S. observer mission.

Previous elections have been marred by violence among supporters of different political parties that at times sparked sectarian conflict.

Nigerian security forces are stretched by the Islamist insurgency in the northeast along with communal violence and banditry in other areas in Africa’s most populous nation.

Hours before polls opened, explosions rocked Maiduguri, capital of Borno state, epicenter of the insurgency. In neighboring Yobe, residents of the town of Geidam fled a militant attack around the same time.

Scattered violence and problems with smart card readers that authenticate voters’ fingerprints meant voting in a small number of precincts had to put off to Sunday, Mitchell said.

Seventy-three candidates in all ran for president, though only those from the two main parties - Buhari and Atiku - were seen as having a chance.