– Nigerians vote Saturday for the president and parliament in a closely fought election after a campaign that’s been dominated by a slowing economy and a war against Islamist militants.

The election is testing the stability of a country with an almost $500 billion economy, Africa’s biggest, that’s been hit by a fall in prices for oil and a weakening currency. Attacks by the Islamist militant group, Boko Haram, have killed at least 1,000 civilians this year and prompted a six-week vote delay after the government said it needed time to subdue the insurgents.

President Goodluck Jonathan, 57, a Christian from the oil-rich Niger River delta in the southeast, is the candidate of the People’s Democratic Party, which has governed Nigeria since the end of military rule in 1999. They’re facing a united opposition led by former military dictator Muhammadu Buhari, 72, a northern Muslim who lost four years ago.

The opposition All Progressives Congress describes Jonathan’s government as corrupt, incompetent and a failure in dealing with Boko Haram. The administration has been unable to find schoolgirls kidnapped by the insurgents in the town of Chibok in April last year, and is relying on the armies of neighboring Chad, Niger and Cameroon to help fight the militants.

The PDP says Buhari is too old and that his time as military ruler was marred by human rights abuses.

The tight race and tensions deepened by the delay have raised concern that the defeated candidate’s supporters will react violently as happened after the 2011 vote, when 800 people died. The most recent independent poll put both candidates on 42 percent support.