Brazil’s Supreme Court on Thursday ruled that former President Luiz Inacio Lula da Silva must start serving a 12-year prison sentence for corruption. The court denied his plea to remain free until he has exhausted all possible appeals, Reuters reported.

Silva is considered one of Brazil’s most popular politicians, and had over 80% approval ratings when he left office in 2011, The Guardian reported. Ahead of elections in the country in October, Silva has been leading opinion polls.

Silva, whose social policies are believed to have helped millions out of poverty, has maintained that the charges against him were politically motivated.

After a 10-hour discussion, judges of Brazil’s top court voted six to five to reject his petition to stay out of prison while he appeals the corruption conviction, AP reported. The Supreme Federal Tribunal’s decision means Silva will not only be forced to start serving the sentence, but will also have to stall his plans to run for re-election this year.

The leader is yet to be tried for several other corruption charges against him.