More results are expected shortly from Nigeria’s tightest election since the end of military rule in 1999.
So far, only one of the 36 state results has officially been declared, leading to growing frustration.
The electoral commission has apologized for the unresponsiveness of the results viewing page on its website, saying a surge in use caused technical hitches.The delays are partly a result of the election continuing for a second day in parts of the country.
The election on Saturday saw voting start several hours late in many areas, and also attacks on some polling stations.
More than 87 million people were eligible to take part, making it the biggest democratic exercise in Africa.
The election has seen an unprecedented challenge to the two-party system that has dominated Nigeria for 24 years.
Peter Obi from the previously little known Labour Party, Bola Tinubu from the ruling All Progressives Congress (APC) and Atiku Abubakar of the main opposition Peoples Democratic Party (PDP) are all seen as potential winners. There are 15 other presidential candidates.
The only result officially declared so far is from the south-western Ekiti state which saw a clear victory for Mr Tinubu in one of his strongholds.
The earliest a winner has been announced is on the third day after voting in the previous two elections, but many had expected a faster conclusion this time because of the introduction of an electronic result transmission system.
This was meant to increase transparency and make sure the results could not be altered by creating a digital version on the website of the electoral commission, Inec.
But many voters have accused electoral officials of refusing to upload the results at the polling units as they are supposed to.
Officials complained of a lack of internet in some places to upload the results, but voters have shared videos and images shared where Inec officials refused to upload the results.
There have also been reports of disturbances at Inec collation centres in some states, with some political parties on Sunday asking their supporters to go to such places to protect their votes.