Sergio Moro, a former anti-corruption judge and leading third-party candidate in Brazil's presidential election, announced Thursday he is ending his campaign.

Moro had emerged as a key "third way" candidate against poll-leading former president Luiz Inacio Lula da Silva on the left and far-right presidential incumbent Jair Bolsonaro ahead of October's election.

But with polls placing him at only eight percent, the 49-year-old opted to end his campaign and "facilitate negotiations between political forces of the democratic center in search of a single presidential candidacy."

"I renounce my presidential candidacy and will be a soldier of democracy to recover the dream of a better Brazil," said Moro, who served as justice minister under President Bolsonaro, on Instagram.

In 2017, Moro sentenced Lula, the current frontrunner in polls, to prison for corruption, though he was released in 2019 and Brazil's Supreme Court annulled those convictions last year.

Moro has also clashed with Bolsonaro, resigning from his government in April 2020 and accusing the president of interfering in police investigations involving his relatives.

Former judge Sergio Moro, seen here in June 2019, announced on Thursday March 31, 2022 that he would end his campaign for Brazil's presidency
Former judge Sergio Moro, seen here in June 2019, announced on Thursday March 31, 2022 that he would end his campaign for Brazil's presidency AFP / EVARISTO SA

"Brazil needs an alternative that frees the country from extremes, instability and radicalization," said Moro, who also announced he would be leaving the centrist Podemos party to join center-right Uniao Brasil.

At the moment, none of the third-party candidates poll above 10 percent, meaning a head-to-head runoff between Lula and Bolsonaro is highly likely.

Political scientist Andre Pereira Cesar, with consulting firm Hold, thinks Moro's departure will benefit the incumbent president.

"Who wins is Bolsonaro, because the voter who would vote" for candidates of a so-called third way "has many more affinities" with him, he explained.

"That voter would never vote for Lula, for ideological reasons," added the analyst, who predicts a runoff between Lula and Bolsonaro is 95 percent likely.

According to the latest survey by the Datafolha institute, Lula remains clearly in the lead, with 43 percent, ahead of Bolsonaro's 26 percent.

Bolsonaro is gaining ground though, reducing the gap from 26 to 17 points compared with the institute's previous poll, in December.