The two major defeated candidates in Nigeria's disputed election on Thursday challenged the victory of ruling APC party's Bola Tinubu, with one rival appealing to courts and the other calling the results "a rape of democracy".
Tinubu, a former Lagos governor of the ruling All Progressives Congress (APC), was declared winner of Saturday's election with 8.8 million votes and the required number of ballots across two-thirds of Nigeria's states.
Almost 25 million people cast a ballot on Saturday in a vote that was largely peaceful but marred by long delays and the slow arrival of online results, angering voters and opposition parties who claimed massive vote-rigging.
The ballot pitted Tinubu, 70, against former vice president and main opposition candidate, Peoples Democratic Party (PDP) hopeful Atiku Abubakar, and a surprise third party candidate, Labour Party's Peter Obi, who excited younger voters with his campaign of change.
On Thursday, Obi, a former governor, said he would challenge the outcome of the election in court, claiming he would prove to Nigerians he had won the presidential race.
He won the third largest number of votes, at 6.1 million, according to official results announced Wednesday -- a significant feat for an outsider in a country where two establishment parties dominated since the end of military rule in 1999.
"We will explore all legal and peaceful options to reclaim our mandate. We won the election and we will prove it to Nigerians," Obi told reporters in the capital Abuja.
Tinubu, a political kingmaker whose influence earned him the nickname "Godfather of Lagos", is set to succeed two-term President Muhammadu Buhari, who steps down in May.
He faces immense security and economic challenges in Africa's most populous country.
PDP's candidate Abubakar, who lost his sixth bid for the presidency, denounced Tinubu's victory describing it as "rape of democracy."
The election "was grossly flawed in every material particular and as such, must be challenged by all of us," Abubakar said.
Abubakar said he was consulting lawyers to decide on his next steps.
Candidates who want to submit legal challenges have 21 days following the announcement of results to bring their case to the courts.
President-elect Tinubu on Wednesday called on his rivals to "join hands" with him, "so that we may begin the task of rebuilding our national home together."
Nigerian elections have often been marked by fraud allegations and violence.
In a bid to address some of those concerns, the Independent National Electoral Commission (INEC) this year introduced biometric voter identification for the first time at the national level as well as IReV, a central online database for uploading results.
But some voters and opposition parties said failures in the system when uploading tallies allowed for ballot manipulation and disparities in the results.
International observers, including from the European Union, also noted major logistical problems, disenfranchised voters and a lack of transparency by the INEC.
An umbrella group of Nigerian civil society organisations and observers said the process "cannot be considered to have been credible."
"Given the lack of transparency, particularly in the result collation process, there can be no confidence in the results of these elections," The Situation Room coalition said.
Glitches with the new technology caused huge delays and queues, discouraging some people from voting.
With a number of registered voters at 93.4 million, the INEC said turnout was just over 27 percent -- even less than in the previous 2019 election.
Obi, who for many especially young Nigerians represented hope for change, said the vote "will go down as one of the most controversial elections ever conducted in Nigeria."
"The good and hardworking people of Nigeria have again been robbed by our supposed leaders whom they trusted."
‘It's my turn'
The INEC has dismissed claims that the process was not free and fair.
Tinubu campaigned on his experience as Lagos governor from 1999 to 2007, campaigning under the slogan "It's my turn" to govern Africa's largest economy.
But critics have voiced concerns about his health, past graft accusations and ties to Buhari, who was criticised for failing in his vow to make Nigeria safer.
The country is facing serious security threats, from a grinding Islamist insurgency in the northeast, bandit militias in the northwest and separatist tensions in the southeast.
The government has also struggled to address a flagging economy, inflation and high unemployment.
Although Nigeria is Africa's largest oil producer, the country imports nearly all its fuel due to a lack of refining capacity and spends billions of dollars subsidising petrol each year -- an unsustainable cost that Tinubu has promised to scrap.