N’DJAMENA, Chad (AP) — Chad’s opposition leader says he has filed an appeal with the country’s constitutional council to challenge the preliminary results of the May 6 presidential election.

In social media posts Sunday, Succès Masra shared a copy of a receipt showing that documents had been filed with the council.

The election’s preliminary results showed President Mahamat Deby Itno won with just over 61% of the vote, and runner-up Masra had over 18.5%.

Masra, the prime minister of Chad’s transitional government, had claimed victory shortly before the announcement and alleged that election results were being manipulated. He hasn’t publicly shared evidence to support his claim.

A Chad-based human rights law expert, Rakimdon Jacques Houitouto, told The Associated Press that if the constitutional council finds Masra’s case convincing, it will consider cancelling the results. It was not clear when the council might decide on the claim.