Nigeria's former military ruler, Ibrahim Babangida, has formally declared he will seek the ruling party's nomination for president.
In comments reported Monday, Babangida said the party accepts that everyone, including President Goodluck Jonathan, has the right to contest the nomination, and that he will "exercise his franchise."
On Sunday, former vice president Atiku Abubakar also said he will seek the nomination of the People's Democratic Party.
The declarations pose a challenge for President Jonathan, who is widely expected to run in next year's election.
Mr. Jonathan took office in May after the death of President Umaru Yar'Adua. PDP members are debating whether Mr. Jonathan, a Christian, should run for a full term or should step aside in favor of a Muslim.
The party has an informal rule of rotating power between Nigeria's mainly Muslim north and mainly Christian south.
Former ruler Babangida seized power in an August 1985 coup. Heruled Nigeria until 1993, when he was forced to step down after his junta cancelled an election.
Some information for this report was provided by Reuters.