Sharon showed "significant improvement" after five hours of emergency brain surgery on Friday, but he is still in serious condition and doctors said he would be kept in a medically induced coma for at least two more days.
Sharon's chief surgeon said it was too early to assess the damage the prime minister suffered after two surgeries to stop brain hemorrhaging in as many days, but independent medical experts said the prime minister's prognosis appeared dire.
Sharon's aides held a grim vigil at the hospital and Israeli elder statesmen Shimon Peres said he is "very worried" about his old friend.
Sharon's illness froze politics across the region, and its repercussions were felt around the world. U.S. Secretary of State Condoleezza Rice canceled a six-day trip to Indonesia and Australia because of Sharon's struggle to survive.
Rice called acting Prime Minister Ehud Olmert on Friday. "Every U.S. citizen, from the President to the last citizen are praying for Sharon's health," Rice said, according to Olmert's office.
"Despite the difficult situation, this evening Israeli citizens have a little more hope," Olmert told her.
Egyptian President Hosni Mubarak also called Olmert on Friday to wish Sharon a speedy recovery, said Olmert's spokeswoman, Haya Perry.
Sharon's sons, Omri and Gilad, were camped out in a room next door to their father's at the neurological intensive care unit. Sephardic Chief Rabbi Shlomo Amar took to the airwaves to advise Israelis which psalms to read for Sharon. "All that is left to do is to pray," Israel's other chief rabbi, Yona Metzger, said.
Shmuel Rabinovitch, rabbi of the Western Wall, said he received dozens of e-mails praying for Sharon's health that he printed out and stuck in the cracks of the holy site. Callers from as far away as Venezuela and the United States asked for advice in praying for Sharon, he said.
Sharon was rushed into the operating room Friday morning after a brain scan indicated rising cranial pressure and further brain hemorrhaging.
Hadassah Hospital director Dr. Shlomo Mor-Yosef said the new surgery Friday helped stabilize Sharon's condition. "Part of the blood clots that remained after the first operation were drained," he said. "At the end of the operation, there is no active bleeding and the intracranial pressure has returned to normal."
Mor-Yosef said a comparison of brain scans before and after the surgery showed "significant improvement," but he did not elaborate.
The chief neurosurgeon operating on Sharon, Dr. Felix Umansky, said he came through the surgery well, but was likely to have suffered damage.