INEC declared PDP candidates winner of the three senatorial seats and nine of the 12 House of Representatives seats in Rivers.
The presidential poll that produced Mr Tinubu has been questioned at the Supreme Court.
“We won the election in Lagos state. We are not accepting the results.”
Per declared results, Mr Obi’s Labour Party won in a landslide in all southeastern states as well as in three South-South States of Edo, Delta and Cross River.
Mr Abubakar spoke at a press conference in Abuja Thursday evening.
Mr Abubakar, who addressed journalists in Abuja Thursday evening, revealed that the outcome of the election would be challenged in court.
The APC leader advised Mr Obi, and other opposition leaders to accept the outcome of the polls as announced by INEC.
The presidential candidate spoke on Thursday.
Mr Tinubu polled 8,794,726 to win the February 25 presidential poll. Mr Abubakar garnered 6,984,520 votes, and Mr Obi 6,101,533 votes.
Peter Obi of Labour Party has maintained slim lead ahead of APC’s Bola Tinubu, in a hotly contested election.
