Lagos - Nigeria's presidential challenger Muhammadu Buhari pledged to cheering crowds in opposition stronghold Lagos that he would tackle the country's three greatest ills - insecurity, inequality and corruption.
Africa's most populous nation votes on 14 February for either Buhari of the All Progressives Congress or President Goodluck Jonathan of the ruling People's Democratic Party.
Corruption
It will be the former military ruler's fourth attempt at the presidency, but this time he enjoys much broader support than before.
As head of the military government between 1983 and 1985 he was seen as tough on corruption and in his dealings with rebellions and armed criminals.
The race is expected to be the most closely fought since the end of military rule in 1999 and the majority ethnic Yoruba south-western states, which voted for Jonathan last time, are seen as crucial swing states.
Civilian rule has since been dominated by the PDP, so its loss at the ballot box would signal an unprecedented shake up of the country's fledgling democracy.
Jonathan was earlier viewed as an easy victor but the momentum has shifted to the opposition in the last few months, with Buhari drawing appeal from a mix of middle class intellectuals fed up with corruption, jobless youths and growing numbers from all walks of life worried about insecurity.
Killed thousands
"The APC has identified three fundamental problems ... insecurity, two - concentration of the economy (in few hands) and three - bribery and corruption," Buhari told thousands of supporters in a packed stadium, many of them wearing T-shirts or traditional, vibrantly coloured robes depicting his face and that of running mate Yemi Osinbajo.
Buhari, a northern Muslim, said he would first tackle the insurgency in the northeast of the country, where Sunni jihadist group Boko Haram has killed thousands in its attempt to carve out an Islamic state in Africa's biggest economy.
Jonathan has been criticised for not doing enough to protect civilians from Boko Haram and for failing to defeat the insurgents.
It is a sign of how under siege Nigerians feel that so many of them regard a military strongman who trampled over civil liberties as the answer to their problems.
