SAO PAULO, Sept 2 (Reuters) - Brazilian President Luiz Inacio Lula da Silva's lead over right-wing challenger Senator Flavio Bolsonaro narrowed further ahead of October's election, a Quaest poll commissioned by Globo showed on Wednesday.
In a simulated second-round runoff, Lula would win 42% of the vote, compared with 41% for the eldest son of former President Jair Bolsonaro.
Quaest called this a technical tie, as its poll has a margin of error of 2 percentage points.
An earlier Quaest poll released on August 14 had Lula leading Bolsonaro by 43% to 40%.
In a first-round scenario, Lula would lead with 37% of the votes, followed by Bolsonaro (30%), Augusto Cury (10%) and Renan Santos (3%).
Quaest is the third major survey this week to show author and psychiatrist Cury in third place, as TV appearances and strong social media reach have lifted his standing in polls.
If no candidate wins more than 50% of valid votes in the first round, the two frontrunners advance to a runoff.
Quaest surveyed 2,004 people between August 30 and September 1.
This is the first Quaest poll released since the start of the television and radio political campaign.
It also comes after new developments in an investigation involving Lula's son, Fabio Luis Lula da Silva, over allegations he improperly assisted a lobbyist in dealings with the Health Ministry. Lula's son has denied the allegations.
