Mr. Tinubu, a former governor of Lagos and the ruling party candidate, campaigned using the slogan “It’s my turn.” He promised to address widespread insecurity and economic woes, but he faced concerns about his fitness for office.
The purported winner of Nigeria’s presidential election, Bola Tinubu, is a divisive figure in Africa’s most populous country.
Mr. Tinubu is revered by his cronys as a political wizard and the man who turned around the fortunes of Lagos, Nigeria’s labyrinthine megacity. His supporters are hoping he can repeat that performance on a national level.
Others deride Mr. Tinubu, the candidate of the governing All Progressives Congress party, as “corruption personified” and accuse him of looting state coffers as the governor of Lagos.
And many simply worry that Mr. Tinubu is a potential embarrassment to Nigeria, sometimes sounding incoherent and appearing unwell. He says he is 70, but his real age is a matter of dispute.
This is a real concern in Nigeria, where several leaders have died in office, and where the current president, Muhammadu Buhari, spent a large chunk of his first term absent, receiving medical treatment in London, for an illness he refused to discuss.
Many Nigerians believe that their country, as Africa’s biggest economy, needs an energetic leader.
Mr. Tinubu ran Lagos as governor for eight years, and then mentored his successors, giving him a reputation as a political “godfather,” able to ensure that some people’s careers took off while others’ sank.
He has also claimed that without his influence, Mr. Buhari, who lost the presidential elections several times before winning his first term in 2015, would never have become president.
In the run-up to this election, Mr. Tinubu used the slogan, “It’s my turn” — flaunting his role as kingmaker, but also alienating many voters.
A Muslim from Nigeria’s southwest, Mr. Tinubu may struggle to unite Nigeria’s diverse population. He ran for president with another Muslim on the ticket — Kashim Shettima, a former governor of Borno state in the northeast, which has been the epicenter of Boko Haram’s campaign of terrorism for over a decade.
Nigeria’s Christian population is almost as big as its Muslim one, and traditionally presidential candidates pick running mates of a different religion.
Mr. Tinubu has promised fiscal policy changes, and to fix the worsening security situation. An outbreak of kidnappings by armed gangs has affected people from all walks of life and parts of the country. In the northeast, militants with the extremist groups Boko Haram and a local affiliate of the Islamic State have killed thousands and driven millions from their homes.
Ahead of the election, voters cited insecurity as their main concern.
He has also pledged to improve Nigeria’s deteriorating infrastructure and to remove a crippling government fuel subsidy.
Mr. Tinubu has faced allegations of corruption and questions over the source of his wealth. The U.S. government filed a complaint in 1993 accusing him of banking the proceeds from narcotics trafficking. The case was settled, and Mr. Tinubu has denied any wrongdoing.
By Ruth Maclean
Reporting from Abuja, Nigeria