Left-wing challenger Luiz Inacio Lula da Silva’s lead over far-right incumbent Jair Bolsonaro has widened slightly three days after Brazil’s polarizing presidential election, according to a poll published on Thursday.

According to the Datafolha Institute poll, Lula has 53 percent voter support versus 47 percent for Bolsonaro — up from a four-point gap (52 percent versus 48 percent) the previous week.

The numbers exclude voters who plan to cast blank or invalid ballots — five percent of respondents, Datafolha estimates. Undecided voters accounted for only two percent.

The margin of error for the poll, which was based on interviews with 4,580 people Tuesday through Thursday, was plus or minus two percentage points.

Lula, the charismatic but ailing ex-president who ruled Brazil from 2003 to 2010, won the first round on Oct. 2 with 48 percent of the vote, versus 43 percent for former army captain Bolsonaro.

The candidates will compete against each other in a final debate on Friday evening.

Bolsonaro and his allies have attacked polling firms, accusing them of bias.

Already in the first ballot, he exceeded the expectations of the pollsters and afterwards boasted triumphantly: “We beat the lie.”

Lula, who turned 77 on Thursday, leads among women (52 percent), the poor and working class (61 percent) and Catholics (55 percent), according to Datafolha.

Bolsonaro, 67, leads among evangelical Christians (62 percent) and more affluent voters (59 percent).