Ghana's President John Mahama has said that he will respect the outcome of Wednesday's tightly contested election.
He also said in a tweet that the Electoral Commission should be allowed to carry out its mandate.
Opposition candidate Nana Addo Dankwa Akufo-Addo, 72, reportedly has an unassailable lead but official results have not been released.
Mr Akufo-Addo has tweeted that the president has phoned him to congratulate him on his victory.
Final results must be declared by 17:00 GMT on Saturday.
The electoral commission announced on Thursday that it was manually verifying the results because its electronic system had been targeted by hackers.
In a tweet, it urged people to ignore the "fake results" circulating on social media.
"I want to assure the nation that we will respect the outcome of the elections, positive or negative," said Mr Mahama.
The ruling National Democratic Congress (NDC) candidate's quest for a second term is facing a strong challenge from a revitalised New Patriotic Party (NPP).
A run-off will be held later in the month if neither of the two main candidates secures more than 50% of the votes.
The campaign was dominated by Ghana's faltering economy.
In the previous election in 2012, Mr Mahama defeated Mr Akufo-Addo by less than 300,000 votes.
NDC candidate: John Dramani Mahama, 58
- Vice-president under President John Atta Mills, who died in 2012. Completed his term
- Now seeking re-election after serving his first term of four years
- Main promise: Launch more infrastructure projects and create jobs
NPP candidate: Nana Addo Dankwa Akufo-Addo, 72
- Campaigned for a return to multi-party democracy under military rule
- A former justice and foreign minister in the NPP government from 2001 to 2007, he is running for president for a third time
- Main promise: Build a factory in each of Ghana's more than 200 districts
Defeat for Mr Mahama would make him the first incumbent to lose an election since Ghana returned to multi-party democracy in 1992.
He has been nicknamed "Mr Dumsor", a local word that refers to the power cuts that have blighted the country during his term, but on the campaign trial has been trying to convince Ghanaians that he is delivering on his promise of creating more jobs.
Mr Akufo-Addo has promised free high-school education and more factories, but his critics have questioned the viability of his ambitions.
The other four candidates include former first lady Nana Konadu Agyeman-Rawlings of the National Democratic Party (NDP), whose husband Jerry John Rawlings initially took power in the 1979 coup.
She is the first woman to run for president in the West African country.
Although the EC is yet to declare the winner, parliamentary results declared at the constituency level show that the NPP has won 107 seats out of 175.
The results for 100 remaining constituencies are still to come.
Four parliamentary surprises
- Minister loses: Veteran politician and Minister of Foreign Affairs Hanna Tetteh lost her seat to former telecoms executive George Andah. In 2014, a tweet by the minister appearing to mock the low turnout of a protest march organised by pressure group Occupy Ghana, which Mr Andah was a member of, attracted criticism from social media users
- A Rawlings in government: Zanetor Rawlings, the eldest daughter of former President Jerry John Rawlings wins her constituency in the Greater Accra region
- Political newcomer: Popular talk show host Kojo Oppong-Nkrumah wins his constituency with a wide margin
- The youngest lawmaker: 23-year-old Francisca Oteng-Mensah of the NPP will be the youngest MP