Nigerian Vice President Atiku Abubakar has confirmed he will run for president in next year's elections.
The announcement sets up a possible contest between Abubakar and current President Olusegun Obasanjo, who has refused to rule out running for a third term.
Nigeria's parliament is debating a constitutional amendment that would allow presidents three terms in office instead of two.
Abubakar came out against a third term for Mr. Obasanjo on Thursday. A presidential spokesman then called on Abubakar to resign, saying if he is going to criticize the administration he should not be a part of it.
In a statement, Abubakar said he supports the administration's reform programs. But he added that he would modify them so they can be better implemented in the interest of the country and its people.
Corruption, religious tension, and militant attacks in the oil-producing Delta region are some of the problems Nigeria's next president will likely face after the election next year.