[BRASÍLIA] An impeachment committee was due to vote on Monday on the fate of Brazilian President Dilma Rousseff ahead of a decisive vote in the lower house of Congress on whether she will face trial.
Bad-tempered debate, interrupted by heckling and chanting, filled the committee room in Brasilia while security forces mounted a huge operation outside to separate rival demonstrators expected in the capital later this week.
The committee was due to vote later on Monday. The room overflowed with journalists and politicians, most of whom displayed placards reading alternately "Time for impeachment" or "Impeachment without a crime is a coup."
Paulo Pimenta, a deputy with Ms Rousseff's Workers' Party, told AFP that the president expected to lose the committee vote by a margin of about 35-29.
However, the committee vote is non-binding, so focus is concentrated on the crucial lower house vote expected either April 17 or 18.
A two-thirds majority in the lower house would send Ms Rousseff's case to the Senate, which would then have the power to put her on trial and ultimately drive her from office.
Ms Rousseff, accused of fiddling accounts to mask the dire state of the government budget during her 2014 re-election, is fighting desperately to ensure enough support among deputies to stop the process.
The latest survey of the 513 deputies in the lower house by Estadao daily on Monday showed 292 in favour, still short of the 342 needed to carry the motion. The count showed 115 opposing impeachment, with 172 required to impose a defeat.
That left the result in the hands of the 106 deputies still undecided or not stating a position.
With Latin America's biggest country gripped by recession, political paralysis and a vast corruption scandal, the stakes are huge and passions on both sides intense.
A barricade was erected along the Esplanade of Ministries in the capital Brasilia to separate opposing protesters that police expect could number as many as 300,000 during the lower house vote.
More than 4,000 police and firefighters will be on duty, G1 news site reported, and security Monday was stepped up at Congress, with heavy restrictions on access to the building.
If the case is taken up by the Senate after being confirmed by the lower house, Ms Rousseff would have to step down for up to 180 days while a trial is held. Her vice-president, Michel Temer, who has gone over to the opposition, would take the reins.
Mr Temer would also remain president if a two-thirds majority in the Senate votes to depose Ms Rousseff.
Some in the opposition have declared Ms Rousseff politically dead ever since Mr Temer's PMDB party, the largest in Brazil, quit her ruling coalition and joined the pro-impeachment ranks last month.
However, Ms Rousseff, who was tortured under Brazil's military dictatorship, has fought back, helped by ally and former president Luiz Inacio Lula da Silva, who is overseeing frantic negotiations to build an impeachment-proof coalition.
Ms Rousseff has rock-bottom popularity ratings but as the moment of truth approaches, it has emerged that Brazilians are not much keener on her would-be replacement Mr Temer.
A poll by the respected Datafolha institute on Saturday showed that 61 per cent of Brazilians support impeachment, down from 68 per cent in mid-March.
However, 58 per cent also said they would like to see Mr Temer impeached too.
Controversy erupted on Monday with the release - said by Mr Temer's office to have been accidental - of a recording in which he practices the speech he'd give if he took over from Ms Rousseff.
Mr Temer adopts a presidential tone, calling for "unification of the country." Ms Rousseff's Workers' Party called the premature speech evidence of "a brazen coup plot."
Several factors could still turn events on their head in this week's countdown to the lower house vote.
One is the Operation Car Wash probe that has revealed a giant corruption network based around state oil company Petrobras.
A Who's Who of Brazilian executives and high-ranking politicians, including many linked closely to Ms Rousseff and Lula, have been prosecuted or investigated. Lula himself has been charged with money laundering.
The government says that the probe has become a political tool to boost the impeachment drive and Rousseff loyalists fear explosive new revelations before the vote.
Another wild card is Lula. An attempt to name him to the government was blocked in the Supreme Court after accusations that he and Ms Rousseff were conspiring to win him ministerial immunity from the Car Wash prosecutors.
The Supreme Court is due to rule in the near future on whether he can formally enter government and the decision would be sure to make waves - as would new charges or legal action.