Brazil’s electoral court on Friday barred jailed former President Luiz Inacio Lula da Silva from contesting the presidential election in October because of his conviction for corruption, Reuters reported. Lula’s lawyers said they will appeal the decision in the Supreme Court.

A seven-judge panel ruled six votes to one against Lula.

Brazil’s Workers’ Party said it will “fight by all means” to secure his eligibility to contest the elections, BBC reported. “We will present all appeals before the courts for the recognition of the rights of Lula provided by law and international treaties ratified by Brazil,” the statement said. “We will defend Lula in the streets, with the people.”

The former president was leading opinion polls ahead of the October election. He has been in prison since he surrendered to the police in April.

The 72-year-old is considered one of Brazil’s most popular politicians, and had over 80% approval ratings when he left office in 2011, The Guardian reported. He has denied the allegations against him and describes the accusations as a political crime.