Lawyers on both sides of the impeachment trial dividing Brazil made impassioned closing arguments, followed by final speeches from senators, some of them bellowing and gesticulating.
The vote on Rousseff's fate, originally set for Tuesday, was put off to Wednesday and the final debate stretched into the night.
Brazil's first woman president, 68, is accused of taking illegal state loans to patch budget holes in 2014, masking the country's problems as it slid into its deepest recession in decades.
Latest estimates from independent analysts and pro-impeachment senators are that the upper chamber will easily reach the two-thirds majority -- 54 out of 81 senators -- to convict Rousseff. Loyalists say they haven't yet lost hope of saving the Workers' Party president.
"The chances of impeachment not passing and the president being made to step down are virtually nil," said political analyst Adriano Codato at Parana University.
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If Rousseff is forced from office, her former vice president turned bitter foe Michel Temer will be immediately sworn in as president until the next scheduled elections in late 2018.
Temer, 75, took over in an interim role after Rousseff's initial suspension in May and at once named a new government with an agenda shifting Brazil to the right.
Rousseff, in a 14-hour appearance Monday, defiantly urged senators to acquit her, branding impeachment as a "coup."
She said it would amount to a "political death sentence." It would bar her from politics for eight years.
Painful remedy
Lawyers presenting closing arguments on Tuesday could not hold back their emotions as the clock wound down on a crisis that has paralyzed Brazilian politics for months.
A lead lawyer for the case against Rousseff, Janaina Paschoal, wept as she asked forgiveness for causing the president "suffering," but insisted it was the right thing to do.
"Impeachment is a constitutional remedy that we need to resort to when the situation gets particularly serious, and that is what has happened," Paschoal said, rejecting Rousseff's "coup" claim.
"The Brazilian people must be aware that nothing illegal and illegitimate is being done here."
Rousseff's veteran lawyer Jose Eduardo Cardozo retorted that Rousseff was innocent and was being made to pay for her support of a huge corruption investigation that has snared many of Brazil's elite.
"This is a farce," he said in a speech during which his voice alternated from shouts to near whispers.
"We should ask her forgiveness if she is convicted. History will treat her fairly. History will absolve Dilma Rousseff if you convict her," he said.
Unpopular leaders
Recalling how she was tortured under Brazil's military dictatorship in the 1970s, Rousseff on Monday had urged senators during her testimony to "vote against impeachment, vote for democracy... Do not accept a coup."
However, momentum to push her out of office appears unstoppable, fueled by deep anger over Brazil's devastating recession and the vast corruption probe centered on state oil giant Petrobras.
Public reaction to the impeachment trial has been marked by widespread indifference, as Brazilians struggle with rising inflation and unemployment.
The Workers' Party under Rousseff and her predecessor Luiz Inacio Lula da Silva is credited with raising 29 million Brazilians out of poverty.
But many now blame the party for the country's ills, accusing Rousseff of mismanagement in particular.
Temer, of the center-right PMDB party, has earned plaudits from investors since taking the interim post. However, it remains uncertain whether he will have voters' support to push through the austerity reforms he promises.
Rousseff has barely double digit approval ratings. But Temer is hardly more popular, according to opinion polls.
If sworn in Wednesday, Temer is expected to leave for China to represent Brazil at the G20 international summit, sources close to him said.
