Haddad, who is standing in for ex-president Luiz Inacio Lula da Silva -- the popular politician was barred from running while serving a 12-year prison term for corruption -- insisted in an emotionally charged rally that he can still pull off a come-from-behind victory.
"This thing is going to turn around," Haddad, 55, told a crush of thousands of white-clad supporters in the largest shantytown in Sao Paulo, a city he formerly served as mayor.
"Brazil still remembers," he added -- a pointed reference to Bolsonaro's outspoken nostalgia for the military regime that ruled Brazil with an iron fist from 1964 to 1985.
Haddad is promising voters a return to the golden years under Lula, who slashed poverty while presiding over an economic bonanza from 2003 to 2010 -- before the economy went bust and his Workers' Party, along with most of the political class, got bogged down in the slime of several massive corruption scandals.
Bolsonaro, 63, meanwhile harks back to a different past: the efficient, if brutal, military dictatorship.
In a country disgusted with massive corruption, violent crime and economic malaise, his message has sold better than Haddad's.
He has also successfully presented himself as an anti-establishment outsider, despite the fact he has served in Congress for the past 27 years.
But he repulses a large part of the electorate -- and many outside the country -- with his overtly misogynistic, racist and homophobic rhetoric.
Bolsonaro made his final campaign pitches Saturday on social media -- as he has done since he was stabbed in the stomach by an assailant at a rally last month.
"The day when we'll win back our independence is almost here, the country's first step toward justice, employment, security and freedom," he tweeted.
The latest poll, published Thursday, gave Bolsonaro 56 percent of the vote, to 44 for Haddad.
Final polls will be published Saturday evening.
![33 passengers and one crew member died on the dive boat, Conception [Brian van der Brug/Los Angeles Times/AP]](data:image/svg+xml;charset=utf8,%3Csvg%20xmlns%3D'http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg'%20width%3D'300'%20height%3D'172'%20data-ring-placeholder%3D'1'%3E%3C%2Fsvg%3E "33 passengers and one crew member died on the dive boat, Conception [Brian van der Brug/Los Angeles Times/AP]")