The main challenger in Ghana’s presidential election has said he is confident of victory but called on supporters to give the electoral commission more time to do its work.

Nana Akufo-Addo spoke to supporters to Accra Thursday as the electoral commission slowly released provisional results from Wednesday’s presidential and parliamentary elections via Twitter. But there were reports that hackers have targeted the commission’s website in order to compromise it and swing victory to a particular candidate.

The main opposition NPP party, citing its own tabulations, has declared Akufo-Addo the winner of the election, and five other opposition candidates have followed suit. However, incumbent President John Mahama and his ruling NDC party have not conceded defeat.

The electoral commission said it believes the electronic transmission of results from polling centers has been compromised, and is only releasing results when it receives physical documents from the field.

“The duty we owe the people of Ghana is not to declare results quickly but to declare accurate results that reflect will of the people,” the commission tweeted.

Calls have mounted on social media for the electoral commission to speed up the vote-counting and declare the final results. Akufo-Addo appealed to his supporters to remain calm.

Nana Akufo-Addo, presidential candidate of the opposition New Patriotic Party, after casting his vote during the Presidential and parliamentary elections in Kibi, eastern Ghana, Dec. 7, 2016.

Nana Akufo-Addo, presidential candidate of the opposition New Patriotic Party, after casting his vote during the Presidential and parliamentary elections in Kibi, eastern Ghana, Dec. 7, 2016.

President Mahama is seeking a second term as leader of the West African country, a major exporter of oil, gold and cocoa.

Akufo-Addo, a former foreign minister, has seized on Ghana’s current economic woes as a campaign theme, accusing Mahama and the NDC of incompetence.

Ghana Incumbent President, John Dramani Mahama candidate of the National Democratic Congress, second left, validates his name before casting his vote during the Presidential and parliamentary election, in Bole Ghana, Dec. 7, 2016.

Ghana Incumbent President, John Dramani Mahama candidate of the National Democratic Congress, second left, validates his name before casting his vote during the Presidential and parliamentary election, in Bole Ghana, Dec. 7, 2016.

Mahama’s term has been overshadowed by the plunge in global oil prices, which reduced government revenues and contributed to soaring inflation. The government accepted a $918 million bailout from the International Monetary Fund.

Ghana is considered one of the most stable democracies in Africa, having witnessed several peaceful transfers of power since 1992.