Photographer: Patricia Monteiro/Bloomberg

Brazil’s jailed former President Luiz Inacio Lula da Silva gained popular support in the latest opinion poll, but may face challenges in getting his likely heir elected if he is barred from running in the October election.

Lula, who is serving a 12-year sentence for corruption, garnered 37.7 percent of voting intention in the MDA poll released on Monday, compared to 32.4 percent in the previous May survey. But not even two out of 10 Lula supporters would pick former Sao Paulo Mayor Fernando Haddad as their candidate, the poll showed. Lula is widely expected to be barred from running, and Haddad would take his place.

Lula backers would be mostly split among Haddad, environmentalist Marina Silva and former Ceara Governor Ciro Gomes -- with the latter two receiving 11.9 percent and 9.6 percent of his votes, respectively. That situation may change as TV adds start being aired next week and the popular former president is associated with Haddad.

The transfer rate of votes currently “reflects the rate of familiarity with the candidate more than his bid, which will require support of ex-president Lula,” said Rafael Cortez, a political analyst with Tendencias consultancy in Sao Paulo. “That will happen throughout the campaign.”

The poll is the first one since presidential hopefuls registered with authorities and started their street campaigns for the most uncertain election since Brazil’s return to democracy. The survey also comes on the heels of protests in favor of Lula, who remains influential despite the fact that he’s been sentenced for corruption and money laundering. The former head of state has repeatedly denied wrongdoing, and his backers say his punishment was politically motivated.

Bolsonaro Edges Up

The poll showed former Army captain Jair Bolsonaro backed by 18.8 percent of respondents, up from 16.7 percent in May. Marina Silva had 6.5 percent of vote intentions, compared to 7.6 percent previously. Former Sao Paulo Governor Geraldo Alckmin, with 4.9 percent of votes, overtook left-wing candidate Ciro Gomes, now with 4.1 percent.

A separate Ibope survey released by newspaper O Estado de S. Paulo on Monday evening showed Bolsonaro in first place with 20 percent in a scenario without Lula, followed by Silva with 12 percent. Haddad trailed with four percent. When Lula is included, he would lead vote intentions with 37 percent.

The MDA poll was commissioned by the National Transportation Confederation, known as CNT, and was based on 2,002 interviews carried out between Aug. 15-18. It has a margin of error of plus or minus 2.2 percentage points.

The Ibope poll surveyed 2,002 people on Aug. 17-19 and has a margin of error or plus or minus two percentage points.

— With assistance by Matthew Malinowski, David Biller, and Ney Hayashi Cruz