Polling stations opened on Saturday for Africa's biggest election as over 70 million Nigerians vote for a new president. 

Incumbent Goodluck Jonathan, from the south, is seen as the front-runner despite a poor performance in last week's parliamentary elections by his People's Democratic Party. 

His main challenge is expected to come from Muhammadu Biharu from the north. Nuhu Ribadu, also from the north, is another main contender. 

The Nigerian government has repeatedly promised the elections will be credible; but earlier problems forced the vote to be postponed.

In a country where vote rigging, violence and intimidation have been common, how genuine will Nigeria's election really be?

Inside Story, with presenter Ghida Fakhry, discusses with guests: Dapo Oyewole, the executive director of the Centre for African Policy and Peace Strategy; Patrick Wilmot, a political commentator on African affairs; and Jonathan Offei-Ansah, the editor of News Africa. 

This episode of Inside Story aired on Saturday, April 16, 2011.

Source: Al Jazeera