Brazil's Senate will vote on Wednesday on whether to put President Dilma Rousseff on trial for breaking budget rules, amid expectations she will become the country's first leader in more than two decades to be removed from office.
If her opponents garner a simple majority of the 81 senators, Rousseff will be suspended for up to six months during the trial and Vice President Michel Temer will take power.
With well over half of senators telling newspapers they will vote to try Rousseff, Brazil's first female leader is expected to leave the Planalto presidential palace on Thursday, following 13 years of leftist Workers Party rule in Latin America's largest economy.
The political crisis has hit at a time when Brazil had planned to be shining on the world stage, as it prepares to host the Olympic Games in Rio de Janeiro in August.
Senators are due to start discussion of the motion at 9 a.m. (1200 GMT) after each member of the upper house gets the chance to speak. The final vote is expected to take place around 8 p.m.
Rousseff, who has said her impeachment is illegal and branded it a 'coup,' has vowed to fight the process until the last minute. Her government appealed to the Supreme Court on Tuesday.
"I will not resign, that never crossed my mind," Rousseff said in a speech on Tuesday, to cheers from supporters.
Brazil is struggling with its worst recession since the 1930s and the country's biggest-ever corruption scandal - a long-running probe into a vast kickback scheme at state-run oil company Petrobras.