DAKAR, Senegal (AP) — Senegal’s top opposition leader suffered a major setback in his quest to contest the presidency on Friday when a top court upheld the defamation conviction in a case brought against him by a government minister.

The Supreme Court’s ruling against Ousmane Sonko’s appeal is the latest twist in a prolonged legal battle that the opposition leader has alleged is to stop his presidential bid in the February elections.

“The trial was the very last chance,” Sonko’s lawyer Khoureychi Ba said of the ruling delivered after a session that started on Thursday. “I realize that Mr. Sonko’s opponents have succeeded in eliminating him from the Feb. 25 presidential election,” Ba said.

Sonko, who finished third in the country’s 2019 presidential election, is widely seen as the main challenger to President Macky Sall’s ruling party. Sall himself ultimately decided not to seek a third term in office after Sonko’s supporters launched months of protests that at times turned deadly.

It was not immediately clear if Sonko still had any chance to take part in the election. The Senegalese electoral code provides that such a conviction makes one ineligible for a presidential race. Still, the final decision rests with the Constitutional Council that rules on all the candidacies, including that of Sonko.

Sonko is currently in prison on a different charge, and will continue to face the six-month suspended prison sentence handed him when he was convicted in the defamation case last year.

El-Hadji Diouf, a lawyer representing Mame Mbaye Niang, the minister who filed the defamation suit against Sonko, celebrated Friday’s ruling as a “big, important win.”

“The minister’s lawyers won on all counts. The six-month suspended prison sentence was upheld. ... We are celebrating our victory,” said Diouf.

Sonko’s presidential bid has faced a prolonged legal battle that started when he was accused of rape in 2021. In June, he was acquitted of the rape charges but was convicted of corrupting youth and sentenced to two years in prison, which ignited deadly protests across the country. Senegalese authorities also dissolved Sonko’s political party in late July and detained him.

After overcoming one of his last remaining legal hurdles in December when a ruling that effectively barred him from contesting the presidency was overturned, Sonko formally submitted his candidacy to beat a Dec. 26 deadline. Eligible candidates will be announced in the first two weeks of January and the campaign season kicks off the following month.