The announcement comes at the start of what could be Mr. Chávez’s most challenging re-election campaign since he first took office in 1999, and it seemed bound to unsettle the political landscape. Although he previously said that he had beaten cancer, questions about Mr. Chávez’s health have continued, including whether he would be able to campaign or stay in office if he were re-elected. “I am in good physical condition to face this battle,” Mr. Chávez said on Tuesday, appearing to tear up as he spoke of not wanting his supporters to suffer on hearing the news of his setback. He spoke in a live television broadcast while touring a truck factory in his native state of Barinas, in western Venezuela. During his remarks, the socialist president did not mention the political campaign or the election, which is scheduled for October, but he sounded a warning to critics who might take pleasure at his misfortune. “Let no one be alarmed, and, I would say, let no one be happy, because independent of my personal destiny, this revolution, as Bolívar said one day, has gotten its start, and nothing and no one can stop it,” he said. He denied reports and rumors that his cancer had spread to his liver or other parts of his body, or that he was dying. “On the contrary, and it is good news,” he said. “I do not have metastasis anywhere.” Mr. Chávez, 57, was given a diagnosis of cancer last June and underwent two operations in Cuba, followed by chemotherapy. His illness forced him to be absent from the country for long periods and tamped down his fiery presence, leading many to wonder whether he would be able to hold off the opposition during its electoral challenge. Luis Vicente León, a political analyst, said that Mr. Chávez had built his political strategy around convincing the public that he had recovered from cancer. If he is able to keep campaigning, Mr. León said, he will in one sense be at a disadvantage against the opposition candidate, Henrique Capriles Radonski, 39, whose youth and energy will be accentuated in comparison with a weakened Mr. Chávez. The president has never said exactly what kind of cancer he had, and his illness and treatment have been shrouded in mystery, which has fueled more doubts about his health. Those rumors spiked in recent days, as opponents of Mr. Chávez speculated on Twitter that he had been rushed to Cuba for an emergency operation. While the government made no official statement before Mr. Chávez’s appearance, the information minister, Andrés Izarra, called the rumors a “dirty war” in a Twitter post. Mr. Chávez said that he was responding to those rumors by making his announcement a day earlier than planned. He said that he flew to Cuba over the weekend for a regular medical exam and that doctors had found a lesion about two centimeters in diameter in the same place that the tumor was found last year. He has said in the past only that his operation was in the pelvic region. Mr. Chávez said that the new operation should take place in the next few days and that doctors would perform tests to determine whether the lesion was malignant. He said Tuesday night that the procedure would take place in Cuba.
