President Nicolas Maduro decreed Dec 8 "the day of loyalty and love" to commemorate Chavez's final speech and public appearance last year, three months before he died of cancer.
This year's holiday falls on the same day as elections for mayors across Venezuela that are being billed by the opposition as a referendum on Maduro's seven-month rule.
Vicente Diaz, one of five members of the National Electoral Council and the only one who frequently criticises the government, denounced Tuesday's decree. In a message posted on Twitter, he called the holiday a "rude display of electoral opportunism."
"It would be a sign of weakness to yield to blackmail," he said after attending a military cannon salute to remember the eight-month anniversary of Chavez's death.
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While Chavez's legacy is never far from Maduro's lips, the government has stepped up efforts to keep him in the public eye as it tries to manage an economic crisis that has emboldened the opposition.
On Monday, the government outlined plans to create a circuit of state-funded museums, a "Chavez route," taking tourists from the former president's birthplace on the plains of Venezuela to his final resting place in the former military barracks in Caracas where he commanded a failed 1992 coup.