By Tim Cocks
ABUJA (Reuters) - Nigeria's former military ruler Muhammadu Buhari declared he would run for president on Wednesday, criticizing President Goodluck Jonathan's administration for corruption and failing to tackle the Boko Haram Islamist insurgency.
His bid for the opposition ticket, if accepted, would pit him against Jonathan for a second time.
Addressing thousands of cheering supporters in a white traditional robe, dark glasses and a green skullcap, Buhari berated the government for failing to stamp out insecurity.
"Nearly all are in fear of their lives ... due to insurgency by the godless movement called Boko Haram, by armed robbers on the highways, by kidnappers who have put whole communities to flight," he said in his bid in the capital Abuja for the All Progressives Congress (APC) ticket.
Thousands have died in Boko Haram's increasingly bloody campaign to carve an Islamist state out of the religiously-mixed country, Africa's biggest economic power and oil producer.
Jonathan, a Christian southerner, has yet to officially declare his intention to run, but is widely assumed to be going for another term. Abuja is festooned in smiling campaign posters touting his achievements and calling for "continuity".
"I ... present myself before you ... and before God seeking to be elected as APC's Presidential candidate," said Buhari, a Muslim northerner.
Buhari won a rare reputation as a fighter against corruption during his timing ruling Nigeria from 1983-85. Most Nigerians agree he did not use the presidency to enrich himself and his backers. His iron-fisted administration jailed several politicians on graft charges.
He had been expected to run and faces ex-vice president Atiku Abubakar in the primaries on Dec. 2. Abubakar declared his intention to run late last month.
Jonathan's assumed intention to run has been welcomed by elites from his powerbase in the largely Christian south but has upset many in the mostly Muslim north, who argue he tore up an unwritten rule that power rotates between north and south every two terms, when he ran in 2011.
Jonathan took over from northern leader Umaru Yar'Adua, when he died in 2009 during his first term.
At the start of this year the opposition coalition was looking stronger than any has since the end of military rule in 1999, after a wave of defections from the ruling party, including by Abubakar and several lawmakers.
But failure to agree on who should lead the party in the polls has made it look weaker and more divided. Jonathan meanwhile faces no opposition within the ruling People's Democratic Party (PDP), which also poached some APC members.
The PDP issued a statement "welcoming" Buhari, but strongly disputing his criticisms of the government, defending its record on agriculture and power generation but not mentioning Boko Haram.
"The APC is hell-bent on using every opportunity at its disposal to discredit the PDP in its quest for political control," PDP spokesman Olisa Metuh said.
If Buhari wins the ticket but loses the poll, he is likely to become a lightning rod for northern anger at the perception that power has become concentrated power in the oil-rich south of Africa's leading energy producer.
More than 800 people were killed and 65,000 displaced in three days of violence in the north after Jonathan's 2011 win.
"Nigeria in my experience has never been so divided, so polarized by an unthinking government hell-bent on ruling and stealing forever whatever befalls the country," Buhari said.
The APC was created out of four regional parties last year. Its core support is in the north and the religiously-mixed southwest, including the commercial capital Lagos, where a formidable chunk of Africa's biggest economy is based.
Buhari is popular in the north, as is Abubakar, but it is unclear whether the mostly ethnic Yoruba southwest would vote en masse for either of them, even while it remains majority APC at the level of lawmakers and state or local governments.
(Editing by Andrew Heavens)