Brazilian Senator Flávio Bolsonaro urged the Trump administration to delay a proposed 25% tariff on Brazilian goods until after October's presidential election, as Brazil's government said trade negotiations with Washington were advancing but ruled out any concessions on ethanol.

Bolsonaro, the right-wing’s likely candidate for the presidency and son of convicted former President Jair Bolsonaro, told a public hearing at the Office of the US Trade Representative (USTR) in Washington on July 8 that "every additional tariff strengthens the very government” it seeks to pressure," according to a report by AFP.

The hearing was part of a two-day session involving roughly 80 participants, called after the USTR proposed in early June a blanket 25% tariff on a range of Brazilian exports following an investigation into alleged unfair trade practices.

President Donald Trump has until July 15 to decide whether to follow through with the tariff. Brazil's Foreign Ministry rejected what it called Bolsonaro's "clear electoral objective" in intervening in Washington, and President Luiz Inácio Lula da Silva, who will be seeking a fourth nonconsecutive term in October, has accused the senator of helping provoke the proposed measure, which the senator denies.

"It is deplorable that, once again, members of the Bolsonaro family are travelling to the US to advocate for foreign interference in Brazil," the government said in a statement after Bolsonaro met with Trump, according to Reuters.

A recent Quaest poll found 47% of Brazilians sided with Lula in the dispute.

In his roughly five-minute address to the USTR panel, Bolsonaro did not raise the issue of ethanol but criticised Brazil's Supreme Court and administrations led by the leftist Workers' Party, attributing to Lula the practices the USTR has cited as grounds for new tariffs, according to a report by O Globo.

He argued that this represented the "worst moment" for tariffs to be imposed, given their proximity to the October vote, and suggested Lula could benefit politically if the Trump administration follows through.

Separately, Bolsonaro submitted a statement to the USTR proposing that Brazil and the US eliminate tariffs on ethanol, arguing the current tariff relationship on ethanol and sugar is "asymmetrical."

Brazil currently applies an 18% tariff on US ethanol, while the US levies a base rate of 2.5% on Brazilian ethanol, Globo reported.

Development, Industry and Trade Minister Márcio Elias Rosa rejected that proposal, saying technical teams from both countries had met earlier in the day and that a further hearing was expected with US Trade Representative Jamieson Greer before Washington's tariff decision next week.

"Never [make concessions on ethanol]. On the contrary, the government of Brazil, President Lula, clearly defends that this ethanol issue not be addressed in this negotiation, and further, that it not be addressed unless we also address the issue of sugar, which is overtaxed in the US," Rosa said, according to O Globo.

The minister said it would be a "shame" if Brazil were to adopt a parity regime with US ethanol, warning that opening the domestic market further to US ethanol would put the sugar and ethanol-producing industry in Brazil's north-east at risk.

Asked about Bolsonaro's participation in the Washington hearing, Rosa was measured: "I think we should focus now — the timeline is short — on what can produce a positive result for Brazil."

Brazil's government struck a more optimistic tone on the broader state of talks. Finance Minister Dario Durigan said negotiations with the US were progressing constructively, with both sides aiming to reduce trade tensions and avoid new barriers on Brazilian exports.

"The talks cover different aspects of the trade relationship, but ethanol is not part of this process and is not being used as a bargaining chip," Durigan said.

He added that Brazil maintains "a solid economic relationship with the US" and believes it is possible to find solutions through dialogue that benefit both economies.

Xinhua also reported that Brazil's government has insisted the country's homegrown instant payment system, Pix, be excluded from the talks, which it said are focused exclusively on trade and tariff matters.

Brazil is among the world's largest producers of sugarcane-based ethanol, while the US leads in corn-based ethanol production; Brasília maintains that regulatory and commercial differences in that sector should be addressed separately from the current tariff negotiation.