Will Lula win Brazil's 2026 presidential election?

Lula, seeking a fourth term, finished second in a first round for the first time since 1998, as wires reported after the October 4 vote. His campaign now has to win over voters who chose someone else, not only turn out its own base. On the record so far, it is framing the runoff around Jair Bolsonaro's conviction and the government's debt relief program, because Lula's own approval, which Quaest put at 43 percent in September, is unlikely to carry him alone.

Flavio Bolsonaro needs to hold what he has and collect the conservative remainder, and he has done most of that. Reuters reported that Ronaldo Caiado and Romeu Zema backed him in the days after the vote (reports differ on whether Caiado's support was formalized immediately or after a meeting and party consultation), and that Augusto Cury, the third-place finisher, endorsed him later in the week. Only Renan Santos stayed neutral. For defeated candidates on the right, backing the first-round leader is cheap and withholding it is costly, so these moves were expected; their speed is the signal.

Reference class: Brazilian presidential runoffs since direct elections returned in 1989. In all seven (1989, 2002, 2006, 2010, 2014, 2018 and 2022) the candidate who led the first round won the runoff, a pattern AFP and other wires noted after the October 4 vote. Lula himself benefited from it in 2022, when he led the first round narrowly and held on. The same rule now runs against him.

The closest analogue is 2022 with the roles reversed: two near-equal camps, a leader with under half the vote and a small block of third-party voters. It breaks in two ways. In 2022 the trailing candidate needed only a sliver of the remaining vote and still lost; in 2026 Lula needs most of what is left, and the largest leftover blocs came from candidates who have since endorsed Flavio. And the 2026 first-round gap, about 1.87 points by our calculation from the reported shares, is the smallest a Brazilian runoff has started from, so the historical record is a weaker guide than its unbroken streak suggests.

Version 1 started from an incumbent base rate of 0.75 and a near-tied runoff average, and landed at 0.46. Two of our signposts then fired. The right outperformed the final polls by more than 3 points on the margin: Datafolha's last first-round survey had Lula ahead 45 to 42 on valid votes, and the count had Flavio ahead by about two, a miss of about five points on the margin, our calculation (signpost: minus ten points). Caiado and Zema then endorsed Flavio (signpost: minus 3 to 5). Applying those gives roughly 0.32, our calculation.

Then the runoff polls arrived, and a third signpost fired: Flavio's lead widening to 6 or more on valid votes. On valid votes, Datafolha (reported October 9) had him about 52 to 48 and PoderData about 53 to 47, our conversion of their total-vote figures, for an average lead of about 5 points, our calculation. With a runoff polling error of about 4 points on the margin, a 5-point deficit gives Lula about 0.11 by a normal approximation, our calculation. The outside view agrees: first-round leaders are 7 for 7, and Laplace smoothing of 0 of 7 gives (0 + 1) divided by (7 + 2), about 0.11, though every earlier leader started with a wider gap. Cury's endorsement and the 2022 and 2026 pattern of polls understating the right push down; the record-small first-round gap and eleven days of campaigning push up. We land at 0.12, our calculation, below Kalshi's 0.18 from October 5.