Brazil’s Supreme Court has ordered a probe into whether right-wing presidential candidate Flavio Bolsonaro issued defamatory statements about his election rival, President Luiz Inacio Lula da Silva.

On Wednesday, a decision from Justice Alexandre de Moraes was published, allowing the Federal Police to proceed with an investigation into posts Bolsonaro published in January.

Bolsonaro, at the time, responded to news that the United States had abducted Venezuelan President Nicolas Maduro with insinuations linking Lula to crimes.

“Lula will be exposed,” Bolsonaro posted on the social media platform X, with screenshots of a handcuffed Maduro and an article about Lula.

He then predicted that the left-wing alliance known as the Sao Paulo Forum would collapse in scandal.

“It is the end of the Sao Paulo Forum: international drug and arms trafficking, money laundering, support for terrorists and dictatorships, rigged elections,” Bolsonaro wrote.

There are limitations to the freedom of speech in Brazil, and under its penal code, defamation can be a criminal offence. Prosecutors have the option of seeking heightened penalties for defamation against presidents or heads of state.

The Federal Police have a period of 60 days to carry out their initial investigation.

But in a statement to local media, a spokesperson for Bolsonaro, a senator for Rio de Janeiro, denounced the probe as a violation of his rights.

“The senator limited himself to reporting facts and detailing crimes for which Nicolas Maduro was arrested and is being prosecuted internationally,” the statement said, adding that there was no “direct criminal accusation against” Lula.

Bolsonaro and Lula are currently in a neck-and-neck race for the presidency ahead of October’s general election.

A poll released this week from the research firm Quaest shows Lula slightly ahead in the first round of voting, with 37 percent of the vote compared with Bolsonaro’s 32 percent.

But if the race proceeds to a run-off, the frontrunner flips. Bolsonaro polls slightly ahead in a one-on-one contest against Lula, netting 42 percent support compared with the incumbent’s 40 percent.

The poll has a margin of error of about 2 percent, though, meaning the results are not conclusive. There is also nearly five and a half months until the first round of voting on October 4.

Both Bolsonaro and Lula are well-known quantities in Brazil’s political sphere.

For the 80-year-old Lula, this year’s race will see him run for a fourth term in office. Previously, he served as president from 2003 to 2011, and then he ran again in 2022, defeating Senator Bolsonaro’s father, Jair Bolsonaro, the incumbent president that year.

The elder Bolsonaro is currently serving a 27-year prison sentence for attempting to subvert the results of that election.

The margins were tight in the 2022 run-off, and then-President Bolsonaro refused to concede defeat, instead suggesting that there were “malfunctions” in the electronic voting machines that favoured Lula.

His supporters took to the streets to protest his loss, blockading roads and attacking police headquarters in the capital, Brasilia.

The unrest culminated in an attack on January 8, 2023, against government buildings in the capital, which was seen as an attempt to trigger a military uprising against Lula’s leadership.

Former President Bolsonaro was later convicted in September 2024 of plotting to stay in power, with prosecutors presenting evidence that he and his allies explored options including calling a new election and assassinating Lula.

The former president has denied wrongdoing and accused his adversaries of a political witch-hunt.

In December, his eldest son, Flavio, 44, entered the 2026 presidential race with his father’s endorsement. He has suggested he would seek his father’s freedom as part of his campaign.

Earlier this year, Lula vetoed a bill that would have lowered Jair Bolsonaro’s prison sentence. He has denounced his predecessor’s actions as a coup attempt.