Abuja , Nigeria ( CNN ) -- Nigeria 's incumbent President Goodluck Jonathan looked likely Sunday to win the election , a CNN tally of preliminary results showed . The Independent National Electoral Commission posted on its website the count from 28 of the country 's 36 states and its capital , showing Jonathan with more than 19 million votes , compared to his main challenger -- Muhammadu Buhari -- who had close to 9 million votes . A formal announcement of the results could come as early as Monday . To avoid a runoff , Jonathan must get at least a quarter of the vote in two-thirds of the 36 states and the capital . Nigerians voted Saturday for their president , a week after parliamentary elections were marred by violence and accusations of fraud in Africa 's most populous nation . Jonathan is the front-runner despite a poor performance in those elections by his People 's Democratic Party . He is popular in the Christian and animist south . The former vice president assumed office after President Umaru Yar'Adua died last year following treatment for a kidney ailment in Saudi Arabia . Jonathan has led the nation of about 150 million people since May . About 73 million people were registered to vote . His main challenger , Buhari , is a former military ruler and was a contestant in the 2003 and 2007 elections . He is the candidate for the Congress for Progressive Change and enjoys support from the mostly Muslim north . Other candidates included Nuhu Ribadu and current Kano state Gov . Ibrahim Shekarau . A CNN iReporter in Lagos , who gave her name as Jan Young , said Saturday she expected the race to be tight . `` If the incumbent president wins , it wo n't be a landslide victory but a fair split between the ruling and opposition parties who campaigned for our votes . I also expect our nation would demand accountability from whoever wins at the end of the day , '' she wrote . Saturday 's voting was largely peaceful , in contrast to the violence that characterized the country 's parliamentary elections on April 9 . During that vote , separate bomb blasts ripped through a polling station and a collation center in northeastern Nigeria . Human Rights Watch has estimated that at least 85 people have been killed in political violence so far . A new election chief promised free and fair elections , but the electoral commission was forced to put off elections earlier this year by a week after logistical problems , including party logos missing from ballot papers , were reported nationwide . It was a major setback reminiscent of the nation 's 2007 elections , which the European Union described as filled with rampant vote rigging , violence , theft of ballot boxes and intimidation . Nigeria , Africa 's most populous country and its largest oil producer , is a major supplier of crude oil to the United States , and hosts many Western oil companies and workers . Nigerians voted April 9 for 360 House of Representatives seats and 109 Senate seats . A gubernatorial vote will be held on April 26 .
Incumbent Goodluck Jonathan is the front-runner . The election will be held on May 29. The voting was largely peaceful . Official results could be announced as early as Monday .