Hugo Chávez confirmed on Wednesday that his fourth chemotherapy session is almost complete.
The Venezuelan president also seemed confident that he would not need any further sessions.
Chávez spoke by phone from Havana to hundreds of supporters who gathered at the Riverside Church in New York to pray for his health. Those in the church included Bolivian President Evo Morales and the foreign ministers of Cuba and Argentina.
"Those prayers today have great meaning for me," Chávez said in the call, which was broadcast on Venezuelan state television. "We're closing the fourth round of chemotherapy and with the grace of God, this will be sufficient.
"I'm just about to finish," Chávez said. "It's something malignant that's turning into something benign."
"I promise you I will live," he said.
He supporters chanted: "Oh, no, Chávez won't go!"
Chávez underwent surgery in Cuba in June to remove a tumor from his pelvic region. Since then, he has undergone three rounds of chemotherapy, and has said this should be the final phase.
Chávez has said previously that tests have shown no signs of a recurrence.
Venezuelan Vice President Elías Jaua said Wednesday that Chávez's health was steadily improving.
Chávez "is doing well, better every day," Jaua said.
Based on reporting by the Associated Press.