Hundreds of supporters of Nigeria's opposition People's Democratic Party chanted as they marched to the national headquarters of the Independent National Electoral Commission, or INEC, on Monday to protest the official results of the recent presidential election.
The demonstration, led by presidential candidate Atiku Abubakar and other party officials, was organized to protest last week's declaration of ruling party candidate Bola Ahmed Tinubu as the winner of the February 25 presidential polls.
Protesters, mostly in black, chanted that Abubakar won the vote and said INEC is a fraud that subverted the will of the people.
"We have evidence that we won this election by our own collation but what we're saying, what we're demanding, is that as at this moment, Mahmood Yakubu has not done a review of that collation; he should review the collation. That's our demand," said Kola Ologbondiyan, the PDP presidential campaign committee spokesperson.
Yakubu is chairman of INEC, and has been in office since November 2015.
Paul Ibe, a media adviser to Abubakar, also protested Monday.
"This is the worst conducted election in our democratic history," Ibe said. "There were a lot of expectations. Nigerians were looking for a leader that will bring them together and begin the process of recovery. What we have is actually a robbery."
Heavily armed police prevented the protesters from invading the INEC premises. INEC officials did not at the time address the aggrieved party members.
INEC officials later responded to the protesters and said their grievances will be addressed.
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The presidential and parliamentary elections were characterized by staff delays and system failures. INEC said delays were caused by logistics issues and security threats in some areas.
But INEC's newly introduced voter accreditation machines failed to function properly across many states.
Over the weekend, INEC held a briefing with officials to review the election and better prepare for the gubernatorial polls on March 11.
"As we approach the governorship and state assemblies elections, we must work harder to overcome the challenges experienced in the last elections. Nothing else will be acceptable to Nigerians," Yakubu said at the briefing.
Last week, third-party candidate Peter Obi announced he also won the election and will prove it to Nigerians in court.
On Sunday, the U.S. ambassador to Nigeria, Mary Beth Leonard, said the presidential election failed to meet expectations.
Tinubu has called for unity and says he wants all parties to work with him for a better country.
Experts say that regardless of how things play out, the president will have big issues to deal with, including widespread insecurity, a weak economy, and troubled health and education systems.