Senegal’s top opposition leader has suffered a major setback in his bid for the presidency when a court upheld a 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 intended to stop his participation in the February elections.

“The trial was the very last chance,” Mr Sonko’s lawyer Khoureychi Ba said of the ruling delivered after a session that started on Thursday.

“I realise that Mr Sonko’s opponents have succeeded in eliminating him from the February 25 presidential election.”

Mr 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.

Mr Sall himself ultimately decided not to seek a third term in office after Mr Sonko’s supporters launched months of protests that at times turned deadly.

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

Mr Sonko is currently in prison on a different charge, and will continue to face the six-month suspended prison sentence handed to 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 Mr 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,” Mr said Diouf.

Mr 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 Mr 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, Mr Sonko formally submitted his candidacy to beat a December 26 deadline.

Eligible candidates will be announced in the first two weeks of January and the campaign season kicks off the following month.