The left wins the presidency but has never held a majority in the Chamber

At its peak, in 2010, the left had 181 deputies, just over a third, according to the DIAP count^[2]. In 2002, the year of Lula’s first victory, the PT elected 91, less than a fifth of the Chamber^[6]. In 2026, the left elected 124, around a quarter, according to Poder360^[5]; the PL alone elected 121^[7].

Overriding a veto requires 257 deputies and 41 senators^[8]. In 2023, Congress overrode Lula’s veto of the time-limit rule for Indigenous land claims: 321 to 137 in the Chamber^[9]. In 2016, the Chamber approved the opening of impeachment proceedings against Dilma Rousseff by 367 votes to 137^[10].

Lula gets bills passed: the income tax (IR) exemption up to R$ 5,000 passed the Chamber by 493 to 0^[11]. But he depends on center and right-wing parties. In 2023, he gave Tourism to Celso Sabino (União Brasil) and Sport to André Fufuca (PP)^[3]; in 2025, both parties ordered their members to leave the government^[12].

Up to September 2024, lawmakers’ mandatory budget amendments took 16.8% of the government’s discretionary spending; in 2020, just over 11%^[13]. In June 2025, Congress overturned Lula’s decree raising the IOF, by 383 to 98 in the Chamber: no presidential decree had been overturned since 1992^[4].

Flávio’s PL elected 121 deputies, the largest caucus^[7], and will have 28 of the 81 senators^[14]. On October 6, Flávio said: “We already have a majority in the Senate and the Chamber, so we can change the Constitution to redemocratize the country”. He did not say what he would change^[15].

Amending the Constitution requires 308 deputies and 49 senators, in two rounds of voting^[8]. According to the Poder360 count, right-wing parties elected 276 deputies^[5]. Flávio voted to override Lula’s veto on temporary prison releases^[16] and advocated overturning the IOF decree, saying that, with the tax increase, “the people really cannot take any more”^[17].

In the first round, Flávio had 47.03% of valid votes and Lula, 45.16%: a difference of 2,224,965 votes, the smallest in a presidential contest since 1989^[18]. Caiado, who had 2.18%, and Zema declared support for Flávio^[19].

Since 1989, whoever came first has always won the second round^[20]. A Lula victory on October 25 would be the first reversal^[18]. That is the scale of the task.

In 2024, the PSD elected 885 mayors; the MDB, 853; the PL, 516; the PT, 252^[21]. A study published in the journal Dados measures the weight of this: “the mayor serves as an important campaign organizer for their party’s federal deputies”^[22].

The Constitution sets elections for the first Sunday in October: municipal elections will be on October 1, 2028; general elections, on October 6, 2030^[8]. In 2030, only 27 Senate seats are up for election^[23]. The Chamber has already been elected. The president has not.