Mr. Chávez postponed emergency cancer surgery to return home, meet with his inner circle and announce on television on Saturday, for the first time, that he had picked the man he wanted to lead his socialist revolution when he is gone — something he seemed to suggest might come sooner than his millions of followers would hope.
He flew to Cuba again on Monday to prepare for surgery, news agencies reported.
Mr. Chávez could well recover and remain a potent force, but on Saturday night he seemed intent on smoothing over factions within his party and solidifying support for the man he chose to succeed him, Vice President Nicolás Maduro.
Mr. Chávez, 58, spoke the word “unity” several times during Saturday’s somber, symbolically weighted appearance. To his left sat Mr. Maduro, and behind both of them viewers could see a bust of Mr. Chávez’s hero, the South American independence leader Simón Bolívar (who never realized his dream of unifying a fractious continent).
Mr. Chávez, a charismatic and polarizing leader who has crafted his own brand of socialist revolution in this oil-rich country, has been vague about the nature of his illness since it was first disclosed in June last year. Since then, he has had at least two operations, chemotherapy and radiation treatment. Yet he said on Saturday that doctors had once again found malignant cells, necessitating a new operation.
The fact that he chose to go home to put his political house in order and clear up the long-unresolved line of succession — rather than write about it on Twitter or report it by calling in to a government television show, as he so often has done with lesser policy decisions during his many medical absences — suggests that his doctors have told him that the news is not good.
“This is a huge passing of the torch,” said Javier Corrales, a political science professor at Amherst College.
Even if Mr. Chávez makes a strong recovery after his surgery, Mr. Corrales said, “there’s no question we are in the transition stage, and that’s always incredibly uncertain.”
Mr. Chávez, who has been president for nearly 14 years, was re-elected in October to another six years. His new term is to begin on Jan. 10.
But if he dies or cannot continue to govern before then, the Constitution states that the vice president, Mr. Maduro, would become president and finish out the last days of the current term.
If Mr. Chávez is unable to begin his new term, or if he leaves office within the first four years, then new elections would be called, according to the Constitution.
In that case, Mr. Chávez said on Saturday that he wanted Mr. Maduro to be his party’s candidate, and he asked his supporters to elect him.
“I ask it from my heart,” he said.
New elections could open the way for a new run by Henrique Capriles Radonski, a young state governor who opposed Mr. Chávez in October. Mr. Capriles received 44 percent of the vote and 6.5 million votes, far more than any previous candidate against Mr. Chávez.
But Mr. Capriles is now running a difficult race for re-election as governor of Miranda, which includes part of Caracas, the captial, and one of the country’s most populous states. The election is on Sunday.
He is being challenged by a former vice president, Elías Jaua, and the government and Mr. Chávez’s socialist party have made it a priority to defeat Mr. Capriles, hoping that it will weaken him politically and remove him as a threat.
“If Capriles loses, there will be a battle in the opposition, a struggle for power, and the leaders will call for a change,” said Luis Vicente León, a pollster close to the opposition.
Some polls taken earlier this year showed that Mr. Capriles could beat Mr. Maduro if they ran against each other.
But Mr. León said conditions had changed with Mr. Chávez’s endorsement of Mr. Maduro. If Mr. Chávez were to die or become too ill to continue in office, it could give Mr. Maduro’s candidacy an emotional boost, he said.
But Mr. Maduro, 50, will have difficulties of his own in having to rein in factions within Mr. Chávez’s party. That could include the military and former military officers to whom Mr. Chávez has given a major role in his government.
For the time being, Venezuelans can look forward to more uncertainty.
The country has been obsessed with Mr. Chávez’s illness since it was first revealed. It has been the source of endless speculation and conspiracy theories. Some people even insist that he is not sick and has invented the illness to throw his opponents off guard. His fiercest opponents see his cancer as a sign of hope that his days as president are numbered; his supporters insist that he will recover, and they condemn such grim speculation as necrophilia.
But the last announcement of his need for another surgery, coupled with his call to rally behind Mr. Maduro, takes the nervous focus on Mr. Chávez’s cancer and what it means for the country’s future to a new level.
Several hundred supporters of Mr. Chávez congregated on Sunday in Bolívar Plaza in central Caracas in what was an uncharacteristically subdued gathering, by the standards of his followers. But also on display was their quasi-religious connection with the president — and the refusal among many to acknowledge his mortality.
“He is going to overcome this difficult time,” said Israel Pérez, 32, a law student. “He will be with us forever.”
Nonetheless, would he support Mr. Maduro as Mr. Chávez’s replacement?
“Venezuelans would support any proposal the president asks them to,” Mr. Pérez said.
Andrew Rosati contributed reporting from Caracas, Venezuela.
