The political firestorm ignited by a huge anticorruption investigation and the impeachment of former President Dilma Rousseff should have generated a new wave of Brazilian political leaders. But instead the two main contenders in this year’s presidential election — Brazil’s former president, Luiz Inácio Lula da Silva, and the retired military officer Jair Bolsonaro, a veteran congressman in Brazil’s Chamber of Deputies — represent the past.

Mr. da Silva, who is running his campaign from his jail cell following a conviction on corruption charges, appeals to voters’ nostalgia for the bygone days of political civility and economic boom that are unlikely to return soon. The political landscape and Mr. da Silva’s own reputation are not what they once were.

Mr. Bolsonaro has surged in popularity with about 20 percent of voter support, according to the latest polls, a high percentage in a fractured race. A conservative populist, he has defended the deplorable military dictatorship that governed Brazil from 1964 to 1985 and has justified the use of torture.

There is a diverse group of presidential contenders along the political spectrum between Mr. da Silva and Mr. Bolsonaro. Though they all have their shortcomings, they by and large share a respect for the country’s young democracy. Mr. Bolsonaro, however, has glorified Brazil’s sinister authoritarian past. He is tempting Brazilians to return to a dark chapter in their history.