The frontrunners include former vice president Atiku Abubakar, who has made four previous attempts at the top job, Senate president Bukola Saraki, governor of northern Sokoto state Aminu Tambuwal and Rabiu Kwankwaso, a former governor in northern Kano state.
Officials said at least 4,000 delegates from the 36 states and the capital Abuja were expected to vote at the PDP primaries in the oil hub of Port Harcourt, in the heartland of the Niger delta, in an event due to extend to Sunday.
Speaking on behalf of the other aspirants, Mr Saraki, at the venue of the convention, pledged to support Mr Abubakar. You have stayed on course over the years and truly, you deserve this victory.
Governor Wike thanked all PDP delegates and stakeholders for ensuring a successful and peaceful National Convention in Port Harcourt.
"Exactly 10 months after that pledge, I can, with gratitude to God and utmost humility, report to you that the PDP of today is improved, enhanced and has migrated from an opposition party to a ruling party in waiting".
"I can not do it alone, I need your support, your assistance, I need your understanding and I need your participation.
U.S. weekly jobless claims drop to near 49-year low
The low unemployment rate provided more evidence of a booming economy, which is now in a record eight-year streak of job gains. That gauge includes part-time workers who'd prefer a full-time position and people who want a job but aren't actively looking.
At the end of the day, it is either Atiku or Tambuwal", he said.
He said he is only one man, adding that he can not influence the decisions of all the delegates from 36 states.
"They should come out and vote for President Muhammadu Buhari because as I said, he has done well and in his second term, he will do even better because he will come with the experience of the first term", he said.
"Let me also commend my fellow competitors for displaying a sense of unity, a sense of objective and a sense of commitment".
Mr Abubakar is expected to be the main challenger to Mr Buhari in the 2019 presidential election.
He described President Muhammadu Buhari as clueless, adding that the PDP can not afford to fail at the general election.