John Kerry meets with Nigerian leaders, begs for transparency in forth coming election.

Concerned that Nigeria could face postelection turmoil, Secretary of State John Kerry arrived here on Sunday to urge President Goodluck Jonathan and his principal political rival to respect the results of the coming vote and to discourage their supporters from violent protests.

“There has been a history of violence being fomented by political parties here in previous elections,” said a senior State Department official who declined to be identified under the agency’s protocol for briefing reporters. “We hope that if there is any doubt about the election that they will use their court system and not encourage their supporters to go into the streets.”

Mr. Kerry’s itinerary included meetings with Mr. Jonathan at the State House and with Muhammadu Buhari, a retired general who is strongly challenging the Nigerian president in a nation increasingly fearful of attacks by militants from Boko Haram, a militant group linked to Al Qaeda.

Mr. Kerry’s arrival coincided with a Boko Haram attack in Maiduguri, a major city in the northeast.

The Nigerian public has become increasing alarmed by the army’s inability to stop attacks and kidnappings by the group. Boko Haram already controls much of the northern part of Nigeria, has attacked parts of Cameroon and Chad, and may soon threaten Niger.

The election on Feb. 14 is expected to be closely contested, and it is possible there could be at least one runoff, which would prolong uncertainty about the outcome and potentially open the door to violent protests.

Under election rules, a candidate must get at least 50 percent of the overall vote and 25 percent of the vote in two-thirds of Nigeria’s states to win.

If no candidate wins outright, a runoff will be held a week after the initial vote under the same rules. If there is still not a clear victor, a second runoff would be held seven days later, and the candidate who receives the majority of the votes nationwide would be declared the winner.

An oil exporter, Nigeria has the biggest economy in Africa, but the decline in world oil prices has shaken its economic prospects.

Complicating the voting is Boko Haram. The Independent National Electoral Commission has said that citizens who have been displaced by the fighting but still reside in the same state in which they are registered will be allowed to vote. But that will not help Nigerians who have fled the violence in the north.

If political violence erupts, it could have sectarian overtones, because much of Mr. Buhari’s support comes from the predominantly Muslim north while Mr. Jonathan has support in the mainly Christian south.

Encouraged by Kofi Annan, the former United Nations secretary general, both candidates have issued statements opposing violence.

“That said, there is a propensity for such violence to erupt, and we want to get ahead of it,” said the State Department official.

The American calculation seems to be that any push to expand the military campaign against Boko Haram will need to follow the election.

How the United States plans to help Nigeria regain the initiative against the group remains unclear. The abduction of more than 200 schoolgirls by Boko Haram last April provoked outrage in the United States and Europe. But a breakdown in trust between the United States and the Nigerian military has hampered cooperation against Boko Haram, as have fears that the provision of heavy weapons to Nigerian forces could lead to human rights abuses.

After a meeting this month with his British counterpart, Philip Hammond, Mr. Kerry said the attacks by Boko Haram constituted war crimes and asserted that the United States was planning a “special initiative” to counter the group.