Maduro said he plans to continue Chavez' socialist revolution.
Maduro's main opposition, Henrique Capriles, spoke to thousands of his supporters who gathered in the northern city of Acarigua, the BBC said.
He vowed to right the economy within a year and eradicate official corruption.
"I ask you for the opportunity to show that I can indeed govern and make things right," Capriles told the crowd, promising not to dismantle Chavez's social programs.
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