SAO PAULO (AP) — Former Brazilian President Luiz Inacio Lula da Silva is challenging his corruption conviction, arguing that the judge who convicted him has proven his bias by accepting a cabinet post under a political rival.

The petition filed Monday with Brazil's highest court asks that da Silva's be freed and his conviction overturned.

Da Silva's lawyers have long argued that Judge Sergio Moro was biased against da Silva and that charges against him were trumped up to keep him from becoming president again. Da Silva was leading polls for this year's election, but the conviction prevented him from running.

Instead, the man who had been trailing da Silva was elected. Moro has now agreed to be Jair Bolsonaro's justice minister.