Maradona pledges allegiance to Venezuela's Chavez
Maradona wore a bright red T-shirt emblazoned with the "Yes" slogan of Chavez's campaign and raised his left hand as the president held a "swearing in" ceremony to recruit hundreds of supporters from sports associations.
Chavez told a packed stadium, which included Venezuela's Magglio Ordonez, a Major League Baseball star in the United States, that he needed a more time in office to "turn Venezuela into a real world power in sport."
Chavez closed the rally by hugging Maradona on stage as scores of red balloons were released and fireworks exploded.
Maradona, who last year became coach of his country's national soccer team and is revered by many fans worldwide as one of the best players ever, says he backs South American leaders like Chavez because they work for the poor.
The Venezuelan leader has been in power a decade and should leave office in 2013 if he loses the tight race for the referendum.
Although Venezuela's national teams have had little international success, Chavez has promoted sports and spent billions of dollars hosting major events. Maradona's visit coincided with South America's under-20 championship hosted by Chavez.