Nigeria's main opposition party is to appeal to the Supreme Court over the outcome of last year's election.
Obasanjo won 99% in his home state
Defeated rival Muhammadu Buhari says he was shocked that the presidential election was declared legitimate.
The appeal court declared that there had been some evidence of electoral fraud - but the judges said this would not have changed the final result.
The result was nullified in the Nigerian leader's home state of Ogun as votes cast outnumbered registered voters.
President Olusegun Obasanjo was elected in April last year in a vote that was quickly condemned by observers as being irregular.
Officially Mr Obasanjo won more than 60% of the vote - getting 99% in his home state.
But there he won hundreds of thousands more votes than were actually cast.
And embarrassingly for Mr Obasanjo this result has been cancelled.
But the judge said that because the vote was manipulated in one state it does not follow that the whole election was fraudulent.
It was the second democratic election after 15 years of brutal military rule
Mr Obasanjo's re-election was also marred by violence.
The European Union and the US also condemned serious irregularities.