CARACAS — Venezuela’s Hugo Chavez suffered a new setback in his battle against cancer, forcing his vice president and chosen successor to stay on in Cuba as the president struggles to recover from a respiratory infection.

Chavez, 58, who won a third presidential term on Oct. 7, hasn’t appeared in public since flying to Cuba 21 days ago to undergo surgery for an unspecified form of cancer. He is due to start his next six-year term on Jan. 10, although the government has said the date is flexible.