Brazil's Rousseff slips in poll ahead of October election

BRASILIA (Reuters) - President Dilma Rousseff has lost ground to her main challenger, Marina Silva, less than three weeks before Brazil's presidential election, which will likely be decided in a close second-round runoff, a poll showed on Tuesday.

The survey by the Ibope polling firm said support for Silva, a renowned environmentalist, has remained unchanged at 43 percent, but Rousseff has slipped two percentage points to 40 percent since the previous poll last week. The gap is within the margin of error of the poll and the two are considered in a statistical tie.