President Muhammadu Buhari vowed Friday on the eve of troubled elections that Nigerians would be able to vote in security, despite a week-long postponement and violence in the north of the country.
In a televised address, Buhari promised "adequate security measures are in place" for the ballot.
"You will be able to vote in an atmosphere of openness and peace, devoid of fear from threat or intimidation," he added.
Tempers have been running high since the Independent National Electoral Commission (INEC) announced a one-week delay just hours before voting was due to begin on February 16.
That prompted the ruling All Progressives Congress (APC) and the main opposition Peoples Democratic Party (PDP) to accuse each other of conspiring with INEC to rig the result.
But Buhari himself has been accused of failing to calm nerves, by ordering the police and security services to be "ruthless" against vote-riggers and ballot box snatchers.
His main challenger, Atiku Abubakar, said the comments recalled "the era of dictatorship and military rule" in a pointed reminder of Buhari's past as head of a military government.
Nigerian daily the Guardian on Friday called Buhari's words "rash inflammatory and... regrettable" while the ThisDay newspaper said it encouraged "scare tactics and brute force".
"His statement sounds like that of an army general than a president elected through the ballot," the New Telegraph added.
Security concerns are never far away in Nigeria and the election campaign has coincided with fresh violence in northern Nigeria, blamed on criminal gangs as well as Boko Haram jihadists.
More than 200 people have died since the start of this month alone.
All eyes will be on the nearly 120,000 polling stations when they open at 0700 GMT to see if INEC has overcome logistical difficulties to deliver the correct ballot boxes, papers and results sheets -- and on time.
IT specialists have worked round-the-clock to reconfigure some 180,000 machines that are needed to check biometric identity cards, and allow people to vote.
Just over 84 million voters have been registered this year, although INEC said 11.2 million (13.7 percent) had failed to pick up their permanent voters' cards (PVCs).
There are more people with cards than at the last election. However, the uncollected cards will likely add to fears about a lower turn-out and do little to alleviate persistent fears of fraud.
Many Nigerians travel from commercial centres such as Lagos to their home towns and villages. Fewer people are expected to be able to afford to do so again -- or want to.
At the last elections in 2015, there were 67.4 million registered voters. Buhari, of the All Progressives Congress (APC), won 15.4 million of the 28.5 million valid votes cast.
Repeated delays in the distribution and collection of identity cards this time have led to suspicions of skullduggery and conspiracy between the parties and INEC.
Both the APC and the PDP have been accused of trying to buy the cards, with a view to rig the result.
Thousands of PVCs and card readers have been destroyed in three suspicious fires at separate INEC offices in central and southeast Nigeria.
INEC chairman Mahmood Yakubu has said there is "no evidence that the commission has been sabotaged", despite a whirlwind of accusations that his organisation has been compromised.
Results are due from early next week.
At 76 and 72, Buhari and Abubakar are the oldest of 73 presidential candidates and are standing in what could be the last elections of their long political careers.
Both have been fixtures on Nigeria's political landscape for decades, through the turbulent decades of military government to the return to civilian rule in 1999.
Just over half of all registered voters are aged 18-35, reflecting the country's increasingly young population.
Buhari has again positioned himself as the candidate to tackle multiple security challenges, including Boko Haram, and endemic corruption.
He also wants another four years to complete much-needed road and rail infrastructure projects and expand social mobility schemes, including micro-finance for the poorest.
Abubakar, meanwhile, is seen as a pro-business free marketeer, whose main pledges have been to privatise state-run companies and float the embattled naira currency.
The past has come back to haunt both candidates, with Abubakar dogged by his alleged links to corruption cases in the United States and Buhari claims of creeping authoritarianism.
Earlier this month he suspended Nigeria's chief justice after he was charged with corruption.
But with the Supreme Court he presides over likely to rule on any election petition, many suspected a political motive.