A total of 73 candidates are on the ballot for Saturday
Nigeria made final preparations Friday on the eve of presidential elections, with candidates pitting continuity against reform in a battle between incumbent Muhammadu Buhari and his main rival Atiku Abubakar.
Buhari, the 76-year-old leader of Africa's most populous nation was elected in 2015 on a wave of hope he could defeat Boko Haram Islamists, tackle rampant corruption and boost the economy.
But he faces a stiff challenge from former vice-president Abubakar, 72, amid fears about widening insecurity, claims of creeping authoritarianism, and economic incompetence.
A total of 73 candidates are on the ballot for Saturday -- the sixth election in 20 years since Nigeria returned to democracy after decades of military rule.
Buhari, from the All Progressives Congress (APC), and Abubakar, of the Peoples Democratic Party (PDP), are considered the main contenders.
Campaigning ended Thursday with final rallies in Buhari's home state of Katsina, in the northwest, and Abubakar's native Adamawa, in the northeast.
A record 84,004,084 people are registered to vote.
Also up for grabs are 360 seats in the lower House of Representatives and 109 in the Senate.
Nearly 120,000 polling units are set to open at 0700 GMT and close at 1600 GMT.
No date has been given for the results, but an announcement is expected from early next week.
Electors face a choice between two elderly candidates who have both been part of the political elite for decades and do not mirror the country's increasingly young demographic.
Just over half the registered voters are aged 18-35.
Chief among the criticisms against Buhari is security, with signs of a resurgence of Boko Haram in Nigeria's remote northeast and new conflicts elsewhere.
His anti-corruption campaign has been described as one-sided against political opponents.
Economic growth picked up last year after a recession in 2016 but remains sluggish. The cost of living is high in a country where most of the 190 million people live in poverty despite billions earned from oil.
Abubakar, 72, bills himself as a dynamic, modern, pro-business leader. But the former vice-president faces allegations about links to corruption.
Buhari said in a televised address Thursday that reelection would give him the chance to fulfil his initial promises and complete vital infrastructure projects.
"It is a choice between going back or keeping the momentum of change," he said
For his part, Abubakar pitched himself as "the ticket to development and advancement" and cautioned voters against four more years of "misdirection and maladministration".
"There is no best candidate among them," said Aliyu Jibrilla, a 70-year-old retired teacher in the Adamawa state capital, Yola, adding: "intellectually... they're not up to it".
"It's about time these old people go," added Modibbo Sadiq, a 23-year-old university graduate.
Security and fraud
Security is a constant threat in Nigeria, after previous outbreaks of deadly election-linked violence.
As a precaution, all vehicles have been ordered off the roads from 6:00 am to 6:00 pm Saturday.
Nigeria's police chief Mohammed Adamu said the restrictions were designed to prevent "hoodlums and criminally-minded elements from hijacking and disrupting the electoral process".
With a reinforced police and military presence on the streets Friday, the interior ministry announced that land borders will shut for 48 hours from midday.
Candidates have pledged to conduct peaceful elections and to accept the results, but there have been clashes in the southern state of Rivers.
APC candidates have been prevented from running in the parliamentary and governorship elections in Rivers because of a dispute over their selection.
Vote-rigging has marred previous Nigerian elections, and this year concerns have been raised both the APC and PDP may have sought to buy votes.
Red flags also went up after voter cards were distributed late, or not at all, and three fires in 12 days Independent National Electoral Commission (INEC) offices.
Ahmad Ado Hasan, 21, a tailor and first-time voter in the northern city of Kano, said: "As a citizen, you should vote your choice, not sell your vote.
"God has already destined the winner, we are only to confirm through our votes. So, vote buying is not the answer."