A man walks in front of posters of candidates of Nigeria's President Goodluck Jonathan's People's Democratic Party in Kano. (Reuters)

ABUJA, Nigeria — On Saturday, Africa’s most populous and oil-rich country will go to the polls. The election looks to be the tightest in the 16 years since military rule ended in Nigeria – and it appears likely that the contest between President Goodluck Jonathan and former military dictator Muhammadu Buhari could devolve into violence.

Here are four reasons why the elections are critically important for the country and the region.

1. The results may affect the terrifying Boko Haram insurgency

Nigeria is in the middle of an unfinished counterinsurgency campaign against the Islamist extremists, who have become famous for their acts of brutality, including kidnapping schoolgirls and attacking churches, schools and the police and army. Now, the tide appears to be turning. Militants are on the run. Their territorial control in the country’s northeast has dwindled, thanks largely to the cooperation of the armies of Chad and Niger, which have launched offensives after the rebels crossed into their territories. A fleet of private military contractors are also helping to fight Boko Haram.

But what will become of the anti-Boko Haram campaign after election day? Many here believe that President Jonathan will lose interest in the effort if he’s elected, leaving the rebels to strengthen as they have in the past. If Buhari wins and redoubles focus on the fight, he will still have to transform a military with systemic flaws including poor training.

The next chapter of the Boko Haram fight will be the hardest. Now that militants have fled their former areas of control, they will have to be rooted out of their hideouts in and around the Sambisa Forest – a formidable task. It’s much easier for Boko Haram to wage guerrilla attacks from the forest than to occupy territory. That fight will go on for some time – and will be a massive charge for whomever is elected.

2.  What happens in Nigeria doesn't necessarily stay in Nigeria

What happens in Nigeria will resonate across the region. It is the largest economy on the continent, and an exporter of film and music to its neighbors. As President Obama said this past week, Nigerians “won your independence, emerged from military rule, and strengthened democratic institutions.”

If Nigeria’s elections devolve into violence or result in deep political division, the financial engine of West Africa will slow. The continent’s biggest oil-producer will be disrupted. Neighboring countries, whose own economies are linked to Nigeria’s through imports and exports, will suffer. And political uncertainty will no doubt creep across borders.

3. The elections could provoke violence. Lots of it.

There’s a good chance that things will not go well. After Nigeria’s 2011 election, nearly 1,000 people were killed in three days of rioting. Supporters of Buhari, who also ran that year, were accused of carrying out protests which “degenerated into violent riots or sectarian killings,” according to Human Rights Watch.

Flaws in the electoral process fueled allegations that the elections were illegitimate. According to International Crisis Group, the polls were “riddled with malpractices, logistical deficiencies and procedural inconsistencies.”

This time, those same challenges exist, but the contest appears to be far closer – what many consider a recipe for postelection violence. Already, Buhari’s party has said that if Jonathan is declared the victor, it will set up a “parallel government.” There will almost definitely be legal challenges, no matter the result. Many Nigerians are already arguing that millions have been disenfranchised by the ongoing fighting, which has left them displaced and without voting credentials.

In Nigeria’s history, an incumbent has never lost a presidential election.

The ethno-religious regional divide in Nigeria is already pronounced between the mostly Muslim north (and its Buhari supporters) and the Christian south (and its Jonathan suporters). Disputed elections could worsen that tension, playing on the idea that the next president will marginalize the area outside of his power base.

4. Nigeria badly needs a good leader.

The next president of Nigeria faces a series of enormous challenges, even beyond Boko Haram. Oil production, which accounts for 70 percent of Nigeria’s economy, is no longer as profitable as it once was. The wealth that has been generated here has not been shared – rather it has been concentrated in the oil-rich south, from which Jonathan hails.

Nigerians are outspoken about the failings of the country’s corrupt public institutions. Billions in oil revenue, for example, have disappeared. The wealthy fly private jets while the bulk of Nigerians continue to struggle financially. Security forces are theoretically allocated billions, but somehow are poorly outfitted.

Now, Nigerians will choose between a former dictator who is remembered for detaining his opponents (Buhari) and the incumbent (Jonathan) who many see as responsible for the country’s most recent failings. It’s a choice that could be bitterly divisive.