Other Latin American markets were slightly down as investors started pricing in prospects of higher US rates, which cut the appeal of higher-yielding emerging market assets.
Brazil's Bovespa index rose for a third consecutive session, climbing as much as 0.5 percent to 54,549.50, its highest intraday level since Oct. 30, 2013.
Traders said investors were betting that upcoming opinion polls would show growing chances of a second round in Brazil's October presidential elections.
Rousseff, whose interventionist policies have been highly criticized by investors, remains a favorite to win the vote but her lead has fallen in recent polls.
Contributing the most to gains on the Brazilian bourse were shares of state-run companies such as Banco do Brasil and Petroleo Brasileiro SA, or Petrobras, which are expected to benefit from less government meddling in their businesses.
Shares in Banco do Brasil, the nation's largest bank by assets, jumped 2.7 percent while Petrobras' stock rose 0.7 percent.
Other Latin American bourses were in the red as US 10-year yields hit a one-month peak, sapping investor appetite in emerging market assets in general. Mexico's IPC stock index dropping 0.2 percent, while MSCI's index for Latin America was practically unchanged.
In currency markets, the Brazilian real edged 0.15 percent higher to 2.2261 per dollar, keeping gains that had been fueled by a central bank announcement that it would extend its currency intervention program past June 30.
Mexico's peso, on the other hand, weakened 0.1 percent to 13.0475 per dollar. The Mexican currency has been slowly sliding since the country's central bank unexpectedly cut interest rates on Friday.
Chile's peso led losses in Latin America, dropping 0.8 percent to 554.00 per dollar.
The move came on the back of a sharp sell-off in the price of copper, the country's main export, which was hit by concern about the impact of an investigation into metal financing in China.