CARACAS, Venezuela - Nicolas Maduro has been sworn in as Venezuela's acting president, against the objections of the political opposition who say the move violates the country's constitution.

Late President Hugo Chavez designated Maduro as his successor before he died Tuesday of cancer. Maduro had been Chavez's vice president.

The country's 1999 constitution says the National Assembly speaker becomes interim president in the event of a president-elect's death or inability to be sworn in. The constitution also says new elections should be called within 30 days.

Maduro has been picked as the presidential candidate of Chavez's socialist party.