Updated

Brazil's presidential candidates are set for their final debate before this weekend's election.

The top two challengers to President Dilma Rousseff are expected to go on the attack against her as she's solidified her recent lead in the polls.

A Datafolha poll released Thursday night says Rousseff leads top challenger Marina Silva 48-to-41 when voters were asked who they would support in a runoff. An Ibope Institute survey puts Rousseff ahead of Silva 43-to-36 in the same scenario.

Rousseff trailed Silva by 10 percentage points just a month ago.

The president's Workers Party has used its deep pockets and highly organized apparatus nationwide to attack Silva's record as a senator and question whether she has the mettle to lead the globe's seventh-largest economy.