Brazil's Supreme Court is considering possible corruption charges against a key congressional leader — a step that could weaken efforts to impeach President Dilma Rousseff.

Eight of the court's 11 justices have already voted to allow charges against Eduardo Cunha. The head of the lower house of Congress is accused of taking $5 million in bribes involving a contract by state oil company Petrobras. Three other justices could finish voting Thursday.

Only the Supreme Court can bring charges against top public officials in Brazil.

Cunha is one of the bigger names implicated in the widespread corruption scandal involving alleged billions of dollars in bribes.

Analysts say charges against him would undermine the effort to impeach Rousseff over allegations she violated fiscal responsibility laws. Cunha has been leading the impeachment effort.