The southern Christian known for his trademark black, wide-brimmed hat has chalked up a string of successes: steady economic growth, an improved railway system, privatized power generation to boost the country's erratic electricity supply and increased local participation in the oil and gas industry.

But Jonathan, 57, and his conservative People's Democratic Party  (PDP) have been tainted by corruption allegations and stand accused  of having been ineffective in the fight against Islamist terrorist group Boko Haram, which has killed an estimated 13,000 people since  2009.

Jonathan's rise to power was unexpected.

A low-profile vice president, he was thrust into the spotlight when president Umaru Yar'Adua, also a Christian, fell ill and died in May 2010. Jonathan finished Yar'Adua's second term.

A few months later, Jonathan was Nigeria's first politician to announce his political candidacy on Facebook, for the 2011 elections.

The declaration caused friction within Africa's most populous nation of an estimated 178 million people. Jonathan's candidacy disregarded the PDP's tradition of alternating presidential power between north and south - and thereby Christian and Muslim – after two terms of office.

--Sapa-dpa--