Chavez, 58, has been receiving treatment for cancer in Cuba and Venezuela but hasn't revealed details of his illness or the nature of the cancer that has seen him undergo chemotherapy and other procedures.
Chavez won the election against the toughest odds since he came to power, partly because of growing public concern over his health. Disillusionment over his socialist policies, expressed by Venezuela's middle- to high-income groups, was swept aside by populist fervor over Chavez's Bolivarian revolution.
Chavez has maintained his constituency of supporters through an elaborate string of subsidies on essential goods, financed by Venezuela's oil revenues.
Chavez's promotion of Foreign Minister Nicolas Maduro, 44, as vice president was the first major reshuffle in the Venezuelan government that has been running the state operations while Chavez has spent lengths of time in Cuba undergoing cancer treatment.
Maduro has long been cited as a successor to Chavez and was frequently at his side during the ups and downs of the president's year of cancer treatment. Chavez never relinquished political power, even when he was away from Caracas for medical procedures.
Maduro, a former trade unionist, takes over from Elias Jaua, another trusted Chavez aide who is widely tipped to challenge and try to wrest the state governorship of Miranda from defeated presidential candidate Henrique Capriles.
The December vote for the governor's post is widely seen as a critical test for Chavez's continuing mandate as well as the future strength of Capriles.
Capriles is rallying opposition support for his campaign to defend his gubernatorial post as a riposte to Chavez after his election defeat by 11 percentage points.
Capriles said he had recovered from the election debacle and was ready to confront the ruling party again. Capriles won 44 percent of the vote compared to 55 percent for Chavez.
While Chavez is seen grooming his loyal aide as a future president, Venezuela's opposition sees Capriles as the next potential leader of the Latin American country.
The opposition coalition parties control seven of 23 states and want to increase their representation in the December polls.
In contest, Chavez aides say they are confident of staging a rout of the opposition and reducing their share of the power in the states.
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