The electoral commission in Nigeria has postponed the 14 February presidential election by six weeks over concerns about the security situation.
Commission chief Attahiru Jega said he had been told troops would not be available to help patrol the ballot because they would be fighting Boko Haram militants in the north-east.
Nigeria and four other states plan to deploy a joint force of 8,700 soldiers.
The election will now be held on 28 March instead.
President Goodluck Jonathan is facing a strong challenge in the contest.
The postponement is a highly contentious move, the BBC's Will Ross reports from Lagos.
Officials from the main opposition party accuse the military of forcing the electoral commission into the delay to help the sitting president's campaign.
It looks set to be a tight race between Mr Jonathan and the former military ruler, Muhammadu Buhari, our correspondent says.
The postponement may well increase the tension which is already palpable, he adds.
