With a marathon 17-hour debate continuing through the night ahead of a vote, the writing was already on the wall for Brazil's first female president.
Only a simple majority of the 81-member Senate is required to suspend Rousseff for six months pending judgement on charges that she broke budget-accounting laws. And shortly after 3:15 am in Brasilia (0615 GMT), the 41st senator declared his intention to back impeachment ahead of the vote.
In the meantime, starting today, Temer was to take over as interim president of Latin America's biggest country -- ending 13 years of rule by Rousseff's leftist Workers' Party.
Temer, from the center-right PMDB party, was preparing to announce a new government and says his priority is to address Brazil's worst recession in decades and end the paralysis gripping Congress during the battle over Rousseff.
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A onetime Marxist guerrilla tortured under the country's military dictatorship in the 1970s, Rousseff has denounced the impeachment drive as a coup and vows to fight on during the trial.
Due to host the Olympic Games in Rio de Janeiro in less than three months, Brazil is struggling to stem economic disarray and handle the fallout from a corruption scandal reaching deep into the political and business elite.
The multiple crises have left the country divided between those blaming Rousseff and those loyal to the Workers' Party, whose transformative social programs have lifted tens of millions of people from poverty.
But Rousseff's chances of escape evaporated yesterday when the Supreme Court denied her attorney general's last-ditch attempt to stop the process.
National divisions were plain to see outside Congress, where police erected a giant metal fence to keep apart small rival groups of demonstrators. Riot police pepper sprayed a group of Rousseff supporters.