Though a far cry from the inexhaustible showman who swept to power in 1998 and has since won two more presidential elections, Chavez is trying to put the cancer behind him and win another term.
"I've had to confront death to fulfill my commitment to the people who I love more than my own life," the 58-year-old socialist leader told adoring supporters in the working-class town of Guarenas. "I won't let you down."
After undergoing surgery for two cancerous tumours, Chavez has defied predictions by some foes that he might not even make it to election day. In July, he declared himself cured for the second time of an undisclosed cancer in the pelvic area and is exuberantly talking up his plans for a new six-year term.
He leads most polls but it looks like a close race and the president has been unable to campaign with the vigour of his younger opponent, Henrique Capriles.
Chavez's events and speeches are much shorter and he has not been crisscrossing the nation as he did in past campaigns and as the 40-year-old Capriles does now.
Instead, Chavez has made quick-fire visits and maximises his exposure with brief, near-daily TV slots where he showers state spending on factories and new homes.
In Guarenas, he inched through the multitudes on the back of a truck, waving and blowing kisses at the crowd. On stage, he sang traditional songs, including one praising the full moon overhead, lifted children into the air in a show of strength, and gave a pulsating stump speech.
By the end of the hour-long appearance on stage, he was sweating profusely under the spotlights.
Despite such efforts, gone are the whirlwind pace and grueling walking tours that took him through rural backwaters and Caracas slums where he earned the love of millions. He is more bloated than usual – from steroids, according to some opposition media – and often disappears out of sight for a day or two.
Some supporters fear this election campaign might be too much of a strain on Chavez's health. Even if he wins on Sunday, the possibility of a recurrence of cancer will hover over him and keep Venezuelans on edge, stoking a long-running guessing game over possible successors inside his ruling Socialist Party.
"The people believe in their leader, but I'm not sure he'll last another term. We have to be prepared," said Ramon Garcia, a 50-year-old shop owner as he sat helping friends who were manning a Chavez campaign booth in downtown Caracas.
"He's a sick man, I can tell, I can see him slowing down. He's making a brave effort," added Garcia, who said he himself suffers from a pancreatic illness and had not yet decided which way to vote on Sunday.
Chavez's precise condition remains a state secret, although most doctors agree that at least two years must pass before a cancer patient can confidently say he is cured.
"His political agenda comes before his personal agenda," said Sunil Daryanani, a Caracas-based oncologist who has not treated Chavez but like many Venezuelans follows any hints about his health closely. "I doubt he's following medical advice very well. But we don't know what cancer he has. He's very cagey."
Capriles, a market-friendly lawyer, is whipping up fervor in this campaign, even mimicking Chavez's old style as he wades through the crowds and knocks on voters' doors. He has drawn the support of a broad coalition of opposition parties and confidently predicts victory.
But Chavez has frustrated Venezuela's opposition time and again – defying huge protests and strikes, and even returning to power after briefly being toppled in a 2002 coup.
His charismatic style, nationalisations in the oil, power and telecommunications industries, and heavy spending on social programs have won him an almost Messianic status in Venezuela's slums, and loyalists are backing him to win again.
"Of course, we are worried about his health," said Juan Gabriel Orozco, who works at a "Socialist Arepa Shop" in Caracas, one of a chain of government subsidized restaurants
"But we know the comandante by heart, and if he says he's healthy enough to run and win, then that's all I need to know."
Chavez barely mentions his cancer any more.
He has been able to make about two dozen visits around Venezuela since the formal campaign began on July 1, far short of the frenetic Capriles' tour of some 300 villages, towns and cities.
Chavez, though, milks every appearance to the maximum.
In the carefully stage-managed show at Guarenas, the ultimate master of ceremonies led the crowd in the national anthem and then roused them with insults hurled at Capriles.
"You loser, you bourgeois," Chavez said, to wild cheers from the crowd. "You will never rule Venezuela!" – Retuers