Rousseff’s testimony will come just hours before a final vote to decide her fate, with everything pointing to her being convicted.
Rousseff, 68, is accused of having taken illegal state loans to patch budget holes. Momentum to push her out is also fueled by deep anger at Brazil’s historic recession, political paralysis and a vast corruption scandal centered on state oil giant Petrobras.
The first female president of Brazil, who says she did nothing worthy of impeachment, will speak for about half an hour, then face questioning.
But it was unclear whether Rousseff will repeat her explosive claim on the Senate floor that the trial is a coup d’etat aimed at destroying her Workers’ Party and restoring the right to power.
“She will go in high spirits. She is calm,” an aide told AFP.
– Showdown -Adding to the sense of a showdown, Rousseff was to be accompanied by heavyweight supporters, including her presidential predecessor Luiz Inacio Lula da Silva, famed singer Chico Buarque and a dozen former cabinet members.
However, there appeared to be little Rousseff could say to save her presidency.
Closing arguments will begin after her testimony Monday, followed by voting, possibly extending into Wednesday. Opponents say they will easily reach the needed two-thirds majority — 54 of 81 senators — to remove her from office.
In that case, Rousseff’s former vice president turned political enemy, Michel Temer, will be confirmed as president until elections in 2018.
He plans to leave Tuesday or Wednesday on his first official foreign trip, a G20 summit in China, where officials say he will push to restore Brazil’s tattered reputation.
– Tortured under dictatorship -Criticized for lacking a popular touch or appetite for backroom politicking, Rousseff has barely double digit approval ratings.
However, busloads of supporters were expected in the capital to protest against what Rousseff has repeatedly called a coup. Activists told AFP they hoped to give her roses.
There is lingering sympathy for Rousseff, who was imprisoned and tortured by the military dictatorship in the 1970s for belonging to a far left urban guerrilla cell.
Although her presidency has been mired in the Petrobras embezzlement and bribery scandal, she herself has never been charged with trying to enrich herself — unlike many of her prominent accusers and close allies.
– Criminal or scapegoat? -The impeachment case rests on narrow charges that Rousseff took unauthorized state loans to bridge budget shortfalls during her 2014 election to a second term.
Allies have spent the Senate trial arguing that these loans were nothing more than stopgap measures frequently employed by previous governments.
Opponents, however, have broadened the accusation to paint Rousseff’s loans as part of her disastrous mismanagement, contributing to once booming Brazil’s slide into recession.
Brazil’s economy shrank 3.8 percent in 2015 and is forecast to drop a further 3.3 percent this year, the worst performance since the 1930s. Inflation stands at around nine percent and unemployment at 11 percent.
Rousseff’s side says that decline was caused by forces far beyond the president’s control, notably a worldwide slump in commodity prices, which hit exports hard.
“There is no basis to say that the president is criminally responsible,” said former economy minister Nelson Barbosa in one of the final pieces of defense testimony on the weekend.
© 1994-2016 Agence France-Presse
A Twitter analysis of Justin Bieber's account found that around half of his followers are fake accounts.