Russia carried out its largest air strike on Ukraine's energy system since its invasion in February 2022, damaging power units at a dam and causing blackouts for more than a million people
Rousseff's support dropped to 36 percent among eligible voters from 38 percent at the beginning of July, as Brazil prepares for elections in October, according to the Datafolha poll.
Support for Aécio Neves, the candidate for the opposition PSDB party, remained unchanged at 20 percent, the poll said, but in a simulation of a likely second-round vote, the gap between Rousseff and Neves narrowed to four percentage points.
The poll broadcast on TV Globo's evening news program has a margin of error of two percentage points either way.