(CNN) -- Nigeria's ruling party has set its presidential primaries for next month, a spokesman said Thursday.
The primaries will be held between October 18 and 20, said Rufai Alkali, a spokesman for the People's Democratic Party.
A single candidate will be ratified on October 23, Alkali said.
On Wednesday, President Goodluck Jonathan said he intends to run, and will make a formal declaration on Saturday.
"In presenting myself for service, I make no pretense that I have a magic wand that will solve all of Nigeria's problems or that I am the most intelligent Nigerian," Jonathan wrote on his Facebook page.
"Far from it. What I do promise is this -- if I am elected president in 2011, I will make a covenant with you, the Nigerian people, to always do right by you, to tell you the truth at all times, to carry you along and most importantly to listen to you, fellow citizens in our communities, and also those of you on this page."
Jonathan's eligibility was in question until last month, when the Peoples Democratic Party said he could run in an open race with other candidates next year.
Under Nigerian "zoning" rules, power must shift to different regions and ethnic groups every eight years.
Jonathan -- who is from the Niger Delta, in the south -- was part of the joint ticket of the late President Umaru Yar'Adua, who was from the north.
Yar'Adua's death in May, after a long illness, upset the order of the zoning. Yar'Adua was elected in 2007 and his southern replacement threatened to halt the north's turn at holding power.
CNN's Christian Purefoy contributed to this report.