Brazilian President Luiz Inácio Lula da Silva and Senator Flávio Bolsonaro remained statistically tied in simulated run-offs ahead of next month's election, two separate polls showed, as fresh survey data pointed to growing economic anxiety among voters even after the government's recent welfare boost.

Right-wing candidate Bolsonaro led Lula by one percentage point in a Quaest poll, while the seasoned leftist leader was ahead by one point in a separate BTG Pactual/Nexus survey, with both advantages falling within the margin of error.

The Quaest poll, commissioned by TV Globo, put Bolsonaro on 42% support in a potential run-off against 41% for Lula, compared with 42% to 40% in the institute's previous survey released on September 14.

It marked, according to Brazilian financial newspaper Valor, the smallest gap between the two candidates in the pollster's entire series, and the first time Lula had numerically trailed his rival in a first-round simulation since the start of the campaign.

In the first-round scenario, Quaest had Lula leading with 37% of the vote, followed by Bolsonaro on 36%, ahead of writer Augusto Cury on 6%, former Goiás governor Ronaldo Caiado on 4%, Free Brazil Movement leader Renan Santos on 3% and former Minas Gerais governor Romeu Zema on 1%.

Undecided voters stood at 8%, with a further 7% saying they would vote blank, null, or abstain.

Quaest surveyed 2,004 people between 17 and 20 September, with a margin of error of two percentage points.

The BTG Pactual/Nexus poll told a similar story from the other direction: Lula would receive 46% of voter support in a run-off against 45% for Bolsonaro, versus a 47%-to-46% lead for Lula in the pollster's September 14 survey.

In a first-round scenario, Lula led with 40% of the votes, followed by Bolsonaro on 37%, Cury on 6% and Caiado on 5%. Nexus surveyed 2,006 people on September 18-20, also with a two-point margin of error.

The tightening race comes amid mounting signs of economic unease. A separate Quaest survey, also reported by O Globo, found that the share of Brazilians who feel their income has grown less than the cost of living over the past year rose to 24% from 21%, while those who felt their income had kept pace, without real gains, fell to 31%; only 10% believed their earnings had outpaced inflation.

The deterioration was sharper among women, a demographic Lula has been trying to shore up, where 25% now report falling behind, up from 21% in a survey conducted just two weeks earlier.

O Globo noted the sentiment aligns with official data: average real labour income, according to Brazil's statistics agency IBGE, fell from BRL3,805 ($745) to BRL3,762 between the quarter ending in March and the one ending in July, the most recent period available, with second-quarter GDP data also showing a drop in consumption.

Separately, Quaest found Lula's government approval held steady, with 50% of respondents disapproving of the administration, unchanged from a week earlier, while approval edged up one point to 44%, Valor reported.

The economic backdrop has fuelled debate over the government's decision last week to raise the minimum Bolsa Família welfare payment by 15%, from BRL600 to BRL691, at an estimated cost of BRL27.8bn between 2026 and 2027.

Finance Minister Dario Durigan defended the move, insisting it did not signal fiscal loosening.

"The Bolsa Família adjustment was based on inflation, not a real increase," he said in an interview with CNN Brasil, adding: "Our commitment is to maintain the trajectory of improvement in public finances."

Estadão reported that Bolsonaro's campaign has accused the government of manoeuvring within the Supreme Federal Court to ensure the adjustment received judicial backing, after Justice Gilmar Mendes validated the measure's legality.