Brasília (AFP) - Brazilian President Dilma Rousseff took off the gloves Tuesday, branding her vice president a traitor and coup-plotter ahead of an impeachment vote scheduled in Congress for this Sunday.

In a blistering speech, Rousseff said: "If there were any doubts about my denunciation that a coup is underway, there can't be now."

Referring to the leak Monday of an audio recording in which her vice president, Michel Temer, practices the speech he would make if Rousseff is impeached, the president said: "The conspirators' mask has slipped."

"We are living in strange and worrying times, times of a coup and pretending and treachery," she said in the capital Brasilia. "Yesterday they used the pretense of a leak to give the order for the conspiracy."

"Yesterday it became clear that there are two leaders of the coup who work together in a premeditated way," she said, without naming names, although the context clearly referred to Temer and the speaker of the lower house, Eduardo Cunha.

Rousseff is in the final stretch of a bruising attempt to save her presidency from impeachment on charges that she illegally manipulated government accounts to mask the effects of recession during her 2014 re-election.

After a congressional committee voted to recommend Rousseff's ouster in chaotic and bad-tempered scenes late Monday, the stage was set for a showdown in the full lower house this weekend.

Deputies were due to start debating Friday, with a decisive vote on Sunday, officials said.

"Voting will begin on Sunday at 2:00 pm (1700 GMT) and we calculate that the result will be late that evening," a spokesman for the speaker's office told AFP.

If the house reaches a two-thirds majority, or 342 deputies, Rousseff's case is sent to the Senate. Anything less, and Rousseff will walk away with her job.

The latest survey of the 513 deputies in the lower house by Estadao daily on Tuesday showed 300 favoring impeachment and 125 opposed. That left the result in the hands of the 88 deputies still undecided or not stating a position.

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- Corruption scandals -

Rousseff is hugely unpopular as Brazil sinks into its worst recession in decades. The political system has also been paralyzed by a huge corruption scandal at state oil company Petrobras.

In the latest arrest in the probe, dubbed Operation Car Wash, a former senator who helped lead an anti-corruption committee was charged Tuesday with taking more than $1.5 million in bribes to help corrupt companies avoid scrutiny.

Rousseff and allies, led by ex-president Luiz Inacio Lula da Silva, have fought back hard in the last few days, describing the impeachment drive as a thinly veiled coup plot.

"I would never have thought that my generation would see putschists trying to overthrow a democratically elected president," Lula, who ruled from 2003 to 2011, told thousands of supporters Monday in Rio de Janeiro.

He singled out Temer, who will take over if Rousseff is ousted, and Cunha, who has been charged with stashing millions of dollars in bribes in Swiss accounts.

However, Lula himself is charged with money laundering in a Car Wash-related case, and supporters of impeachment say that Rousseff's allegedly illegal manipulation of government accounts fits a pattern of incompetence and corruption.

- Impeachment procedure -

If the lower house does approve Rousseff's impeachment, the case goes to the Senate.

The Senate must then confirm it will take the case at which point Rousseff would step down for up to 180 days while a trial was held. Temer, who recently left the ruling coalition to enter the opposition, would take over.

To depose Rousseff, the Senate would need to vote by a two-thirds majority, with Temer remaining president.

After winning Monday's skirmish in the committee, opponents of Rousseff declared they were on a roll.

"It was a victory for the Brazilian people," said opposition deputy Jovair Arantes, predicting that the result would carry with "strong" pro-impeachment momentum into the full chamber's vote.

But pro-government deputy Silvio Costa said he was also confident.

"The opposition is very arrogant" after Monday's committee victory, he said.

There were worries that passions will spill over as the lower house vote approaches. Large crowds of both Rousseff supporters and opponents were expected in the capital Brasilia and will be separated by a metal barrier.

More than 4,000 police and firefighters will be on duty, G1 news site reported, and security has been stepped up at Congress, with heavy restrictions on access to the building.