RIO DE JANEIRO - Brazil's President Luiz Inácio Lula da Silva and his political rival Sen. Flávio Bolsonaro traded sharp words this week over U.S. tariffs, as each tried to steer the Trump administration away from plans to impose 25 percent duties on Brazilian goods even though America enjoys a sizable trade surplus with the South American nation.

The two frontrunners for October's presidential election exchanged pointed remarks about their respective approaches, indicating they view public perception of their handling of the widely disliked tariff proposal as a decisive element in the upcoming vote.

Sen. Bolsonaro, son of former President Jair Bolsonaro, argued that the tariffs would bolster Lula, while Brazilian officials rejected claims that their trade rules are unfair, biased or harmful to U.S. business interests.

The Trump administration first levied a 50 percent tariff on Brazilian imports last July, pointing to a supposed campaign against Jair Bolsonaro, who faced trial for an alleged coup attempt after losing the 2022 election to Lula and was subsequently found guilty.

In his letter, U.S. President Donald Trump also cited unfair Brazilian trade practices and instructed U.S. Trade Representative Jamieson Greer to launch an inquiry that later accused Brazil of weak anti-corruption measures and discriminatory tariffs, among other issues, even though the United States has maintained a goods trade surplus with Brazil for years.

After ties between the two nations seemed to improve following meetings between Lula and Trump last year, the June tariff proposal triggered fresh tensions, prompting Lula to caution the U.S. leader against interfering in Brazil's elections.

The development led Lula to once more champion Brazilian sovereignty, a message that resonated strongly last year and unexpectedly lifted his popularity ratings.

Flávio Bolsonaro highlighted the effect on public sentiment in the submission he delivered to the office of the United States Trade Representative on Wednesday.

Brazilian public polling shows that the incumbent government's electoral standing has improved during times when U.S. tariff pressure has been most prominent, he stated in the filing, which featured poll graphs, while warning that the proposed tariffs would grant the government a political win.

Bolsonaro further suggested that the USTR investigation findings could stand even if implementation were delayed, recommending that tariffs be postponed.

Lula labeled the filing yet another act of disloyalty to the nation.

Jair Bolsonaro's other son Eduardo, who resides in Texas, was found guilty earlier this year of improper lobbying of the U.S. government to pressure Brazilian authorities into halting his father's trial.

It is unacceptable that the Bolsonaro family, through its compliant approach, attempts to place Brazil at the service of United States interests, Lula stated Thursday on X. No justification exists for raising tariffs at this time or in the future.

Three hours afterward, Flávio Bolsonaro posted on X that Lula alone seeks higher tariffs on Brazilian products and declared he would return to the United States next week to press for the additional duties to be dropped.

Addressing the USTR inquiry, Lula's government dismissed several complaints, including the notion that its PIX instant payment platform unfairly harmed rival electronic services, asserting that its measures are legal, impartial and foster competition.

Lula and Flávio Bolsonaro have also differed over the Trump administration's move to designate two major Brazilian criminal organizations, First Command of the Capital (PCC) and Red Command, as terrorist groups.

Sen. Bolsonaro backed the designation, which some analysts viewed as a U.S. effort to influence the election, whereas Lula maintained that the label does not fit because the groups pursue financial gain rather than political objectives.

Earlier this week, the United States announced sanctions against companies and individuals connected to PCC, describing it as the largest transnational criminal network in the Western Hemisphere.