After vowing for months that a conviction on corruption charges would not stand in the way of his bid for a third term as Brazil’s leader, former President Luiz Inácio Lula da Silva surrendered to the police on Saturday evening to begin serving a 12-year sentence.
His imprisonment was an ignominious turn in the remarkable political career of Mr. da Silva, the son of illiterate farmworkers who faced down Brazil’s military dictators as a union leader and helped build a transformational leftist party that governed Brazil for more than 13 years.
His detention was also a momentous development in the coming election in Brazil, upending the race to replace President Michel Temer in October.
Having carved out a sustained and ample lead in the polls, Mr. da Silva promised his followers that the Workers’ Party could once again wrest control of Brazil’s destiny, and prioritize policies to narrow the country’s steep inequality.
Succeeding would have been a stunning comeback after the 2016 impeachment of Mr. da Silva’s handpicked successor, Dilma Rousseff. She was replaced by Mr. Temer, a deeply unpopular center-right politician who also stands accused of corruption.
Mr. da Silva is the first former Brazilian president to be remanded into custody since democracy was restored in the mid-1980s and the first former president to have been convicted of corruption.
His imprisonment represents perhaps the biggest triumph in the yearslong effort by a team of crusading judges and prosecutors to upend the endemic graft that has long been a staple of politics and deal making in Brazil.
Before surrendering to federal police authorities, Mr. da Silva, 72, accused prosecutors and judges of knowingly pursuing a baseless case against him.
“I do not forgive them for creating the impression that I am a thief,” an indignant Mr. da Silva, sounding hoarse, told a throng of gathered outside a metalworkers union headquarters outside of São Paulo. For hours on Saturday, in a tense standoff, his ardent supporters had physically blocked his surrender, before finally allowing him to leave.
The prosecution, Mr. da Silva charged, was an effort to thwart his vision of a country in which ever more poor people could enroll in universities, go on vacation and buy cars and homes.
“If that was the crime I committed, I want to say that I will continue being a criminal because we’re going to accomplish much more,” Mr. da Silva shouted to a crowd that had spent much of the morning chanting that he should not surrender.
During his last hours of freedom, Mr. da Silva appeared to acknowledge that his political career is over — at least for now.
“You will have to transform yourselves,” he told supporters. “They must know that the death of a combatant doesn’t end a revolution.”
Months away from Election Day, Brazil’s political left now finds itself without an obvious standard-bearer.
Mr. da Silva did not anoint a successor to take his place on the ballot, suggesting that Workers’ Party leaders have yet to decide who stands the best chance of filling the void.