Three days before Brazilians choose their next president, a single sentence from the country's top prosecutor has reopened a diplomatic wound that never quite healed. Jorge Messias, Brazil's attorney general, declared on Thursday that foreign interference in national institutions "cannot be tolerated," after the Guardian reported that the Trump administration had pushed to channel more than $175m toward a campaign against Brazil's supreme court. His office has since filed a criminal complaint to investigate the matter, according to the network GloboNews. The timing could hardly be more delicate.

Lula da Silva, the leftist incumbent, is locked in a near-even race against Flávio Bolsonaro, a far-right candidate and ally of Donald Trump. Washington has already tried once to tilt the scales: last year, tariffs and sanctions were deployed against Brazilian officials in a failed bid to halt the coup trial of Flávio's father, former president Jair Bolsonaro, whom Trump branded a victim of a "witch-hunt." The elder Bolsonaro was convicted anyway and sentenced to 27 years for attempting to overturn his 2022 election loss. More recently, Washington has designated two Brazilian criminal organizations as foreign terrorist groups, a move critics see as another lever aimed at weakening Lula ahead of the vote.

For Messias, the pattern amounts to something larger than routine diplomatic friction. "Disagreements between governments are inherent to international relations," he wrote on social media, before drawing a firmer line: interference in "choices that belong exclusively to the Brazilian people" cannot be excused as mere policy disagreement. Whether the complaint leads anywhere concrete remains uncertain, as does its effect on an electorate already weighing economic strain against competing visions of sovereignty.