Reuters has the story:
For an analysis of what a northern Muslim presidency might mean, see here.
Abubakar, 59, is a Muslim from a minority tribe in northeast Nigeria. He is a political veteran of more than two decades who has business interests in oil, insurance and pharmaceuticals.
He had been a leading Obasanjo supporter in the past, but his opposition to a third term for the president could harm his own ambitions. Analysts expect Obasanjo to try to undermine his campaign and stop him from getting the party ticket.