For the first time in the 2026 series of DataTempo polls, Senator Flávio Bolsonaro of the PL party is numerically ahead of President Lula of the Workers' Party in a hypothetical presidential runoff among voters in Minas Gerais, Brazil's second-largest electorate. The fourth round of the survey, released on Friday, September 18, by the newspaper O Tempo, puts the senator at 43% against 41.9% for Lula. The 1.1-point gap sits inside the margin of error of 3.1 points in either direction, which makes the result a statistical tie. Interviews were conducted between September 9 and 12. Flávio Bolsonaro, son of former president Jair Bolsonaro, is a senator for Rio de Janeiro and a leading opposition candidate in the October election.

In the simulated first round, Lula still leads numerically with 35.6% against 31.2% for Flávio, also a technical tie. The clearest trend in the series is the narrowing gap: in August the president had 36% and the senator 28%, so the distance fell from 8.0 to 4.4 points in about a month. In the runoff simulation published in August, Lula had 42.4% against 40.9%.

Why the numbers may have shifted

Mariela Rocha, a political scientist and senior research analyst at the institute, offers one hypothesis: the start of campaign advertising. She notes the poll does not ask voters why they intend to vote as they do, so the explanation remains preliminary.

"Between August and September we entered a phase of greater exposure for the candidacies, with electoral advertising and a succession of political events that can influence how voters form their opinions and preferences. The movement observed in the poll is compatible with this process of the race becoming more defined."

In the spontaneous scenario, with no list of names, Lula gets 30.5% of mentions and Flávio 24.4%, with slight overlap between their intervals. Undecided voters remain a large group: 25.6% named no candidate. Among the trailing names, psychiatrist Augusto Cury rose to 6.8% while former Minas governor Romeu Zema fell to 3.9%; in August the figures were 0.9% and 9.8%. The report cautions against reading too much into that swing, since the confidence intervals of the two rounds still overlap. "Cury may be benefiting from a phase of greater exposure and knowledge of his candidacy, while Zema loses ground in this segment of the race in Minas Gerais," Rocha said.

Methodology and limits

The survey was commissioned by Sempre Editora, the parent company of O Tempo, and consisted of 1,000 face-to-face household interviews. The confidence level is 95% and the poll is registered with Brazil's electoral authorities as MG-00468/2026 and BR-02329/2026. Two limits deserve attention. The sample covers only Minas Gerais, not the whole country. And the confirmed finding is the set of percentages; the explanation about campaign effects is an analyst's hypothesis, raised outside the questionnaire.

For readers tracking polls in the final weeks of the race, three checks help: confirm the registration number with the electoral court, see whether the gap between candidates exceeds the margin of error, and check the field dates, since a poll is a snapshot of that moment. The first round is in October. Brazilians who have not confirmed their voter registration can do so free of charge on the website of the Superior Electoral Court, the TSE.