ABUJA, Nigeria (AP) — Nigeria’s main opposition candidate in this year’s presidential election appealed a ruling that upheld President Bola Tinubu’s victory and asked the nation’s Supreme Court to declare him the winner instead, according to documents seen by The Associated Press on Tuesday.

In the documents filed, the Peoples Democratic Party’s Atiku Abubakar, who came second in the election, said the appeals court which dismissed challenges against Tinubu’s election victory this month “erred in law” by not supporting claims of illegality.

The appeal is the first of three expected from the opposing candidates challenging the election of Tinubu who is attending this year’s United Nations General Assembly as a first-time president. Observers said though the conduct of the election was an improvement from previous ones, delays in uploading and announcing the results might have given room for ballot tampering.

Abubakar said Nigeria’s election commission did not follow the due process in announcing the winner and that Tinubu was not qualified to contest for president, citing allegations of dual citizenship and of a criminal indictment in the United States, all of which the Nigerian leader has denied.

His 42-page notice of appeal urged the Supreme Court to rule that declaring Tinubu as the winner of the presidential election is “unlawful, wrongful, unconstitutional, null and void and of no effect whatsoever … having not satisfied the (legal) requirements” to win. The court should either declare him the winner or direct the election commission to conduct a fresh vote, Abubakar requested.

The date to hear the appeal is yet to be announced.

None of Nigeria’s presidential elections since its return to democracy in 1999 has ever been nullified.

Analysts said this year’s election is different given the adoption of the newly amended electoral law that introduced the use of technology to make the process more transparent.