Opposition leader Henrique Capriles will run for president in Venezuela's April election and is expected to formally announce the decision later today, two sources in his camp said.
"There's a lot of negativity around, it's going to be tough, but we're going to do it", one of the sources told Reuters.
"Henrique's made his decision. He's not backing down."
More than 20 world leaders are expected to attend the funeral today, but there will be no burial as he will be embalmed.
Thousands flocked to the streets of Caracas to see the coffin of Chavez travel through the city to lie in state until Friday's funeral.
A look back at the life of Venezuelan President Hugo Chavez who has died at the age of 58 after a two-year battle with cancer.