BRASILIA (Reuters) - Support for far-right frontrunner Jair Bolsonaro has grown ahead of Brazil's presidential election in October, while second-place environmentalist Marina Silva edged up in a new Datafolha poll released on Wednesday.
Excluding jailed former president Luiz Inacio Lula da Silva, Bolsonaro continues to lead with 22 percent of voter intentions, compared to 19 percent in the previous Datafolha poll in June.
Business-favourite Geraldo Alckmin remains stuck in single digits with 9 percent of support, up from June when he polled just 7 percent.
Lula was registered as a presidential candidate by his Workers Party last week but will almost certainly be barred from running by the electoral court due to his corruption conviction that led to a 12-year jail sentence.
Bolsonaro, a former army captain who favours easing gun controls to fight crime, has stirred controversy with comments denigrating women, gay, black and indigenous people that have landed him in court.
Despite this he has led the field from the outset with Lula excluded, by tapping into voter anger with political corruption.
Support for Lula's running mate Fernando Haddad, the former Sao Paulo mayor who is expected head the ticket in Lula's stead, has risen to 4 percent since June, when he polled just 1 percent.
Haddad's chances of making the second-round run-off between the two most voted candidates will hinge on his ability to tap into the massive support enjoyed by Lula despite his conviction for taking bribes and a half dozen other corruption accusations under investigation.
Voter support for Lula when he is included in the questionnaire has surged to 39 percent from 30 percent in the previous Datafolha survey.
If Lula's name is not on the ballot, the number of voters who say they will spoil their ballot, not vote for anyone or remain undecided fell to 28 percent from 33 percent in June, a variable that makes the Oct. 7 election the most open and uncertain in decades.
Centre-left candidate Ciro Gomes, a former governor of Ceará state in Brazil's poorer Northeast, has held steady at 10 percent compared to the prior poll. Gomes has so far failed to draw the support of Lula voters he would need to become the new standard bearer of Brazil's left.
Datafolha surveyed 8,433 voters across Brazil between Aug. 20 and Aug. 21. The poll has a margin of error of 2 percentage points.
(Reporting by Jake Spring and Anthony Boadle; Editing by Richard Balmforth)