In a 45-minute address to senators who will decide her fate starting Tuesday, Rousseff denied the charges of being "criminally responsible" for alleged fiscal wrongdoing by her administration, and called the accusations "unfair and arbitrary".
At times "overcome with emotion", according to the Agencia Brasil news agency, Rousseff said "never would I violate what I believe, or commit any acts against the interests of those who elected me."
Brazil's first woman president was re-elected to a second term in 2014 by more than 54 million votes, but struggled practically from the day she took office again with an aggressive and empowered conservative opposition that lost by a small margin, a sputtering economy and general discontent with a corrupt governing class.
Rousseff in effect said the trial was in retaliation for her government's efforts to clean up corruption.
"I ensured the independence of the Public Prosecution Service and did not tolerate any political interference with the (investigative) activities of Federal Police. I have opposed interests and now I have paid, and am still paying, a high personal price for the stand I have taken," she said.
Many political observers have noted that Rousseff has never been accused of corruption, unlike numerous lawmakers with the power to vote whether to impeach her or not.
"I am not fighting for my term, for vanity or attachment to power ... I am fighting for democracy, for truth, justice and the people of my country," said Rousseff.
Impeachment requires a two-thirds vote, or 54 of the 81 senators.
Should she be impeached and her ruling Workers' Party ousted, which most observers say is likely, interim President Michel Temer of the conservative PMDB party will see her term through 2018.
Brazil's suspended President Dilma Rousseff speaks during the final session of debate and voting on Rousseff's impeachment trial in Brasilia, Brazil, August 29, 2016. [Photo/VCG]
