Hugo Chavez has named Nicolas Maduro, his vice-president and a radical foreign minister, as his chosen successor after announcing that he was returning to Cuba for cancer treatment.
The Venezuelan president, whose cancer has recurred after two operations, chemotherapy and radiation treatment, said in a televised address from the presidential palace that Maduro, a former bus driver, should succeed "if something were to happen that would incapacitate me".
"My firm opinion, as clear as the full moon - irrevocable, absolute, total - is that you elect Nicolas Maduro as president. I ask this of you from my heart," he added.
Chavez, 58, who has remained secretive about the details of his cancer, said he had suffered a return of "malignant cells" in the same area where tumours were removed before. The Venezuelan government has previously said the problem is in his pelvic area. He won re-election to a new six-year term on October 7 and is due to be sworn in on January 10. The death of a president-elect before taking office would trigger a new election within 30 days.
Maduro, 50, a former trade union leader, has been foreign minister since 2006. After being detained at New York's John F Kennedy airport in 2006, he called the United States a "racist, Nazi government".
Nicolas Maduro: The hard left in Chavez's successor