Some Brazilians relished the imminent arrest of Mr. da Silva, seeing it as a measure of justice in a country where powerful politicians have stolen with impunity for years. But others seethed, saying that the 72-year-old former president, who is the front-runner in the presidential election set to take place in October, was about to become a political prisoner.

Mr. da Silva spent the day holed up at the metalworkers union headquarters in São Bernardo do Campo, a municipality just outside of São Paulo, surrounded by supporters. Though Mr. da Silva did not speak publicly on Friday, a series of posts on his Twitter account conveyed a message of defiance.

“They want to arrest me to silence my voice, but I will speak through you,” one said. Another read: “They want to leave me jailed in a cell so I can’t carry on, but I will move forward through your legs.”

The setting provided a powerfully symbolic backdrop for a pivotal moment of his political career. The headquarters is where Mr. da Silva gained prominence as a union leader in the 1970s by railing against the military dictatorship, and where he and fellow leftist leaders formed a political movement that decades later carried him to the pinnacle of power.

“He is staying positive, he is talking and listening,” said Eduardo Suplicy, a founder of Mr. da Silva’s Workers’ Party who visited with him during the afternoon. “There has been such an outpouring of solidarity from the people. He has received all these men and women crying, but he always managed to say something positive.”