The announcement comes as Lula warns of foreign interference and polls show a tightening presidential race.

Brazilian Senator Flavio Bolsonaro has named conservative Congressman Alfredo Gaspar as his running mate, ending weeks of speculation over who would join his presidential ticket in October’s election against incumbent President Luiz Inacio Lula da Silva.

The announcement on Wednesday also highlighted the challenges facing Bolsonaro’s campaign, which has struggled to build alliances beyond his own Liberal Party and failed in an effort to recruit a woman to the ticket in hopes of broadening its appeal.

Gaspar, 55, has represented the northeastern state of Alagoas in Brazil’s Chamber of Deputies since 2023 and served as its public security secretary.

Accepting the nomination, he described himself as “a simple person from the northeast” whose life had been defined by “hard work and honour”, saying he would work alongside Bolsonaro “to transform Brazil into a fair and decent place”.

Gaspar led a congressional investigation into Brazil’s National Social Security Institute (INSS), the agency that oversees the country’s public pension and social security system. Fabio Luis Lula da Silva, the president’s son, is under investigation over allegations that he received improper payments linked to an alleged pension fraud scheme involving that agency.

Political analyst Lucas de Aragao, a partner at consultancy Arko Advice, said the choice was surprising but gave Bolsonaro someone well-placed to attack Lula on an issue that has become politically sensitive.

“He has the authority to deal with an issue that is uncomfortable for Lula. He also speaks extensively about public security,” Aragao said.

Gaspar emerged as the Liberal Party’s preferred choice after several higher-profile figures courted by Bolsonaro, including Senator Tereza Cristina of the Progressive Party and former Caixa Economica Federal chief Daniella Marques of the Republicanos, failed to get their own parties to support them in joining the ticket.

Bolsonaro, the son of former far-right Brazilian President Jair Bolsonaro, has struggled to expand his coalition, with several centre-right parties choosing to either back Lula’s broader coalition or remain neutral in the election in hopes of maximising their representation in Congress and appealing to anti-Bolsonaro voters in the country’s northeast.

A Quaest survey published on Wednesday found Lula leading Bolsonaro 44 percent to 39 percent in a simulated run-off, down from an eight-point lead in mid-July. In a first-round scenario, Lula was on 39 percent support to Bolsonaro’s 30 percent. If no candidate wins more than half the valid votes in the first round, the top two candidates advance to a run-off.

Launching his re-election campaign on Sunday, Lula cast the October vote as a battle to defend Brazil’s sovereignty amid growing concerns over foreign influence.

“Too many people are poking their fingers into our business. Too many people are interfering in our land. And that is going to stop,” he told supporters.

In July, Brazil denied visas to two US State Department officials who Lula said were being sent to “meddle” in the elections.

The diplomatic rift deepened on Tuesday, when the Trump administration said it was temporarily revoking the visa of Brazil’s ambassador to Washington in response to Brasilia withholding approval for Trump’s ambassadorial nominee.

Lula has pointed to those tensions, along with Trump’s public support for Flavio Bolsonaro and US tariffs imposed on Brazilian goods, as evidence that Brazil’s sovereignty is under pressure.

“As long as I’m president, no one from outside will interfere in Brazilian elections,” Lula said on Wednesday.