Brazil's Supreme Court has rejected a last-ditch attempt by President Dilma Rousseff to halt the impeachment process against her ahead of a key vote in Congress.

The government lawyer says the ruling amounted to denying Rousseff the opportunity to defend herself. The ruling cleared the way for Sunday's vote by the lower house of Congress, which is due to decide whether to send Rousseff to an impeachment trial.

The latest counts of voting intentions in the lower house by major Brazilian newspapers show that the pro-impeachment camp will have the necessary two-thirds majority. If the vote passes on Sunday, the Senate will have the authority to open a trial against Rousseff, who is accused of illegal government accounting tricks.

If the Senate finds her guilty with another two-thirds vote, she would be forced from office.