BRASÍLIA, Oct 23 - Foreign diplomats in Brasilia are discussing a rapid recognition of whoever wins Sunday's presidential runoff, four ambassadors told Reuters, seeking to ward off any attempts from outside the country to call the election prematurely for either candidate.

However, they have yet to formalize a plan, with multiple missions still in discussion with their capitals on how best to proceed, the sources said.

Right-wing Senator Flavio Bolsonaro, former President Jair Bolsonaro's son, holds a small but narrowing lead in polls over leftist President Luiz Inacio Lula da Silva.

Two ambassadors told Reuters that they are worried that US President Donald Trump, or his administration, might question the result if Lula wins by a small margin.

"It wouldn’t surprise me if Trump or (right-wing Argentine President Javier) Milei declare Bolsonaro the winner before electoral authorities do,” said one ambassador, who worried such a scenario could provoke a major institutional crisis.

The ambassador, who spoke on condition of anonymity given the sensitivity of the subject, said they were not involved in discussions with other governments.

The State Department and US Embassy in Brasilia did not respond to questions on whether Trump would commit to recognizing the runoff's winner as confirmed by Brazil's electoral tribunal. The tribunal did not reply to a request for comment.

One ambassador said their concern about Trump comes after the US leader's comments on recent elections in Latin America, including Honduras’ 2025 presidential election. Amid delays in that vote count, Trump alleged fraud without providing evidence and said there would be "hell to pay" if Honduras changed preliminary results that had put his preferred candidate ahead.

A premature recognition from Trump or someone else “could lead to an institutional crisis that nobody wants," the ambassador said. 'FAITH IN THE BRAZILIAN SYSTEM' Memories are still fresh from Brazil's 2022 election, when foreign governments, including the United States, the European Union, and many Latin American countries, played an important role recognizing in Lula’s win over former President Bolsonaro, who refused to concede for days.

The elder Bolsonaro received a 27-year-sentence for plotting a coup after his 2022 election loss lead to his supporters violently storming the capital.

"Our main objective is to recognize the outcome of an election that we expect to be held according to good standards. We have faith in the Brazil voting system," one European ambassador told Reuters, adding that "speed is the main concern." Bolsonaro finished ahead of Lula in the election's first round on October 4, which sent markets soaring on optimism that he was well positioned to win and push through tough economic reforms that favor business with the help of a new Congress packed with allies.

Bolsonaro holds a small lead over Lula in polling heading into the runoff, but polls suggest it is narrowing as the vote approaches.

“If Lula wins, particularly by a small margin, it’s inevitable that at least some will say that the vote was somehow rigged in his favor,” said one ambassador, who said the hypothetical scenario increases the pressure on Brazilian electoral authorities and international observers to quickly confirm the vote’s outcome.

Oliver Stuenkel, a professor at Sao Paulo’s Getulio Vargas Foundation, said a Trump refusal to quickly recognize a Lula victory would be a nadir in bilateral ties. “I think that is a scenario that one has to keep on the radar," he said.

Ambassadors expressed faith in Brazil’s electoral process and institutions, and said concerns were not about any single candidate but about possible election denialism affecting declining confidence in Brazil’s democratic institutions.

“I don’t care if Lula or Bolsonaro wins,” one ambassador said. “I do care about the shape of Brazilian democracy after this election.”REUTERS