Goodluck Jonathan (People’s Democratic Party)
The incumbent president, Jonathan inherited office after the death of his 2007 running mate, former President Yar’Adua. He has never been elected to office in his own right.
A Christian member of the Ijaw ethnic group from the Niger Delta, Jonathan holds a PhD in Zoology and worked as an environmental protection officer and lecturer before entering politics in 1998 as deputy governor of his home state. He rose to the position of governor with the impeachment of his predecessor, and was hand-picked to run on the People's Democratic Party ticket by former president Obasanjo.
Critical to Jonathan’s campaign has been his commitment to end conflict in the Niger Delta – although he introduced an amnesty to the region with some success, the Independence Day bombings last year in Abuja marred his efforts at peace.
Nuhu Ribadu (Action Congress of Nigeria)
A young and relatively inexperienced Northerner, Ribadu is the former Head of the Nigerian Economic and Financial Crimes Commission and has been responsible for the issuing of thousands of indictments, a role which earned him the World Bank's 2008 Jit Gill Memorial Award for Outstanding Public Service.
A Senior Fellow at the University of Oxford, Ribadu returned from a period of self-imposed exile last year after charges of impropriety against him for failing to declare his assets were dropped.
He is viewed as a strong candidate in the southwest of the country.
Gen. Muhammadu Buhari (Congress for Progressive Change)
A former military Head of State, Buhari ruled Nigeria between 1983 and 1985 after overthrowing the government of Shehu Shegari as a key member in a military coup.
Throughout his administration, Bhuari declared a "War on Indiscipline", and is hailed as having restored a considerable degree of public order despite the authoritarian tendencies of his rule. He was removed from power in a coup led by Gen. Ibrahim Babangida, and has since run numerous times for election – he was defeated in the 2003 elections won by Olusegun Obasanjo and the 2006 elections by Umaru Yar'Adua.
A Muslim Fulani, Buhari was voted the candidate for the Congress for Progressive Change at the 2011 election by "universal acclaim", and has considerable support in the northwest.
Ibrahim Shekarau (All Nigeria Peoples Party)
Born in the region of Kano, Shekarau progressed up through the Ministry of Education following careers as a civil servant and a maths teacher, later becoming the governor of his home state.
He has since delivered on a pledge to implement Sharia Law in the area, and in 2004 he became notorious for refusing to sanction polio vaccinations in Kano.
Shekarau has received plaudits for the peace that has sustained in Kano during his tenure as governor.