Chavez himself says these elections for governors and mayors could decide "the future of the revolution, the future of socialism and also the future of Hugo Chavez."
A setback could force Chavez to contend with hostile local-level opponents with revived national clout. Victory would help him lay the groundwork to extend his rule beyond 2013, when his six-year term ends.
Pre-election polls showed Chavez's candidates leading in a majority of races, while the opposition was ahead or in tight races in several of Venezuela's most populous states.
|Chavez's older brother is in a tight race to succeed their father in their home state [AFP]
Teresa Bo, Al Jazeera's correspondent in the capital, Caracas, said: "Everyone is wondering how strong the oppositon is.
"Chavez feels very popular and people continue to love him. His approval rating is around 60 per cent. The big question is not how many states he'll win, but how many he will lose."
Chavez already has a congress filled with supporters and a Supreme Court that critics say is in his pocket as he tries to hold on to power in state houses and city halls.
Chavez has threatened to cut off national funds to states that end up in the hands of opponents. He also has warned he might need to send tanks to defend his government if an opponent wins hard-fought Carabobo state.
Candidates include Chavez's older brother Adan, who is in a tight race to succeed their father as governor of Barinas, Chavez's home state. Chavez's ex-wife Marisabel Rodriguez is also on the ballot - on the opposition side.
Rodriguez, running for district mayor in her hometown, Barquisimeto, said her campaign may be local but it's also "against the danger posed to democracy by leaving a single person in power for a long time."
Chavez's allies swept the last state elections in 2004, winning all but two of 23 governorships and a majority of local offices. This time, candidates are competing for 22 governorships, 330 mayoral posts and other offices.
Chavez's popularity has rebounded since he suffered his only electoral defeat in 2007 in a referendum that would have allowed him to seek re-election indefinitely, as well as hand-pick local leaders and suspended civil liberties under extended states of emergency.
Opposition mayoral candidate Carlos Ocariz, running in the poor Sucre district of Caracas, said in spite of the government's oil-funded largesse, "we've realised that elections are won in the street. They aren't won in news conferences or monopolizing the television screen."
Chavez, meanwhile, has attacked some opponents as "traitors" and "oligarchs." He ordered authorities to make sure opposition leader Manuel Rosales doesn't leave the country «because that criminal has to go to prison."