Abuja - Influential ex-president Olusegun Obasanjo has accused the current leader Goodluck Jonathan of misreading the Boko Haram crisis and allowing the threat to escalate to "gargantuan" heights.
Obasanjo, still a key power broker in the ruling Peoples Democratic Party (PDP), has launched a series of scathing attacks against Jonathan in recent months and has publicly urged him to not seek re-election calls the president has ignored.
"Initially President Jonathan's understanding of the Boko Haram phenomenon suffered from wrong reading and wrong imputation," Obasanjo said at a book launch event late Wednesday.
"That is what led us to where we are today."
He described the five-year Islamist uprising as a "gargantuan danger to the nation" and blamed Jonathan for taking "more than three years" to understand the root causes of the conflict, including poverty and unemployment.
Also read: Regional security meeting ends in Abuja
Jonathan has been roundly criticised for his handling of the Boko Haram conflict but the comments from Obasanjo may take on added significance with less than three months before Nigeria's vote.
Obasanjo plucked Jonathan from relative political obscurity to serve as Umaru Musa Yar'Adua's running mate in 2007 polls.
Jonathan rose to the top after Yar'Adua's death in 2010 following an illness.
Obasanjo called on Jonathan, a southern Christian, to stand aside before the 2015 polls in favour of a Muslim from the north to preserve the PDPs unwritten rule of rotating power in the divided nation.
But after Jonathan fought off his opponents and secured the PDP nomination, some expected Obasanjo to fall in line and support the candidate of the party he helped create in 1998 as the era of military rule was ending.
But in Wednesday's speech, Obasanjo appeared intent on continuing his attacks.
He also slammed the president's economic management, saying that if Nigeria stays on its current course and fails to contain graft, "we will all sink deeper into poverty".
Some Nigerians will likely pay little attention to anti-corruption speeches from Obasanjo, who was widely suspected of misusing public funds during his 1999-2007 tenure.
His current political clout is hard to quantify but experts say that if Obasanjo actively works against the PDP in the coming vote, it could hurt Jonathan's re-election prospects.