Analysts described a committee's recommendation for an impeachment trial as the last formal stage before a Senate vote on the Brazilian president's future. Rousseff is accused of manipulating government finances.
A Senate committee voted 15-5 on Friday in favor of putting the 68-year-old president on trial before the entire parliamentary chamber for breaking budgetary laws.
"The case now goes to the full federal Senate," opposition Senator Raimundo Lira announced following the decision.
The approval means that if Rousseff loses an impeachment vote in the plenary on Wednesday, as expected, she would be automatically suspended and Vice President Michel Temer would replace her as acting president.
The committee's recommendation is nonbinding but marked the last formal stage before the full Senate vote.
In recent weeks, the country's first female president has been preparing to step aside for up to six months while senators decide her fate.
Rousseff is accused of manipulating government financial accounts to mask the depth of the country's economic troubles during her tight 2014 re-election.
But she insisted the charges are trumped up and has promised to "resist to the last day." But even the Supreme Court has rejected government requests to halt the impeachment process.
Rousseff has struggled to survive politically in the face of Brazil's biggest corruption scandal and its worst recession since the 1930s.
Her removal would mark an end to 13 years of leftist rule by the Workers Party that began in 2003 under her mentor, former President Luiz Inacio Lula da Silva.
Next Wednesday's Senate debate and vote is expected to take more than 20 hours, continuing into Thursday, and her suspension would probably take effect next Friday, local media reported.
She would be allowed to remain in her presidential residence but will lose access to the executive offices and will have her pay cut in half. There are still questions over her exact status, including whether she will be able to use military planes for travel.
In a last ditch effort, Rousseff's supporters on the Senate committee attempted to annul the proceedings, pointing out that parliamentary speaker Eduardo Cunha - the man who launched the impeachment process last year - was removed from office Thursday by the Supreme Court for obstructing the investigation of corruption accusations against him.
mm/sms (AFP, Reuters)