Sharon's severe illness in the middle of political campaigns – both in Israel and the Palestinian territories – will further complicate Middle East peacemaking efforts, reports CBS News correspondent David Hawkins.
Doctors said Sharon was to undergo a CT scan Friday morning to determine if the massive cranial bleeding that occupied surgeons for long hours after the stroke had completely stopped. Experts spoke of serious brain damage from the stroke and doubted he would recover.
Sharon's deputy,, immediately took the reins as acting prime minister and tried to convey a sense of stability, convening a Cabinet meeting Thursday morning. But Sharon's dramatic downturn left Israelis stunned and threw his ambitious peace agenda into doubt.
"I'm worried about the future of this country, about everything in this country," said Rafael Levy, a 42-year-old construction engineer from Tel Aviv.
60 Minutes correspondent Bob Simon says the mood in Tel Aviv is dismal.
"It's a nation in mourning. The radio is playing sad songs, television is non-stop coverage. It's mourning and it's shock, and it's very comparable to my mind to the death of [former Israeli Prime Minister Yitzhak] Rabin 10 years ago," Simon said.
Sharon's collapse less than three months before elections left his new centrist Kadima Party, which appeared headed for an easy victory, in limbo.
A poll conducted for Channel 10 TV and the Haaretz daily showed Kadima maintaining Sharon-like figures, far ahead of its main rivals, whether Olmert or two other Kadima notables head the party – but the expert who conducted the poll warned that its results must have been influenced by the shock at Sharon's condition, and the lead might evaporate.
Palestinians reacted with a mix of glee at seeing the fall of their longtime enemy and apprehension at the instability that could follow. Some Palestinian leaders worried that Sharon's illness could derail their Jan. 25 parliamentary elections. "We are watching with great worry at what might happen if he is harmed," Palestinian leader Mahmoud Abbas said. Abbas called Olmert on Thursday to express wishes for Sharon's recovery.
Some Palestinian children gave out sweets in the Gaza Strip at news of Sharon's illness.
Foreign leaders, who embraced Sharon following his unilateral pullout from the Gaza Strip last year, also expressed concern.
U.S. Secretary of State Condoleezza Rice praised Sharon as "a man of enormous courage," and British Foreign Secretary Jack Straw said he was praying for a miraculous recovery. Japanese Prime Minister Junichiro Koizumi postponed a visit to the region scheduled to begin Sunday, and two U.S. envoys who were to arrive Thursday delayed their trip.
Meanwhile, Christian broadcaster Pat Robertson suggested thatfor "dividing God's land."
Iranian President Mahmoud Ahmadinejad said he hoped for the death of Sharon, the latest anti-Israeli comment by a leader who has already provoked international criticism for suggesting that Israel be "wiped off the map."
Sharon underwent seven hours of surgery Thursday at Jerusalem's Hadassah Hospital after suffering a widespread brain hemorrhage. He was to remain in a medically-induced coma and on a respirator for at least two days to give him time to recover before gradually waken him, hospital officials said. His sons, Omri and Gilad, were by his side at the neurological intensive care unit.
Dr. Shlomo Mor-Yosef, director of Hadassah Hospital, said Sharon's pupils were responding to light, "which means the brain is functioning."
Mor-Yosef alsoafter an earlier stroke suffered on Dec. 18, saying Sharon received appropriate doses.
"We are fighting for the life of the prime minister, with no compromise," he said.
Israeli media quoted hospital officials as saying Sharon suffered vast brain damage, and outside experts agreed a full recovery was unlikely. Aides to Sharon said they were working on the assumption he would not return to work.
Two prominent rabbis visited Sharon's bedside on the heavily guarded seventh floor of the hospital and prayed along with his family for his recovery, one of the rabbis, Yitzhak Batzri, told Israel Radio. Batzri's father, leading Jewish mystic David Batzri, held Sharon's hand to direct a prayer toward him, Yitzhak Batzri said.
"He is unconscious as everyone knows and the small happiness that we have is that we saw the family is strong, the family believes, the family is praying and hoping," Yitzhak Batzri said.
Attorney General Meni Mazuz announced that the Israeli election would be held as planned on March 28. Sharon was to face off against the new head of his former Likud Party, Benjamin Netanyahu, and Labor Party leader Amir Peretz.
Sharon had been expected to win in a landslide as head of Kadima, which he formed after bolting Likud last year. Many hardline Likud lawmakers tried to torpedo the Gaza withdrawal and Sharon formed Kadima to free his hands to make further peace moves with the Palestinians.
His illness clouded his party's electoral prospects.
"I can't see another person who will emerge who is as strong as Sharon," said political analyst Menachem Hofnung. "The party is in trouble."
Haim Ramon, a Kadima lawmaker, said the party needed to rally around Olmert.
"We have to convince the public that the group that came together with Sharon will fill the political, ideological, societal void, which is needed for the country to go on," he told Israel's Channel 2.
A snap poll taken Thursday showed that an Olmert-led Kadima would still win 40 of 120 seats, similar to the results under Sharon. Under former Prime Minister Shimon Peres, the party would get 42 seats, according to the Channel 10-Haaretz poll. The number of people polled and the margin of error were not given.
Main rivals Labor and Likud received 13-18 seats in the Dialog poll.
Dialog director Camille Fuchs said Kadima's impressive results might not hold through the three-month campaign, since they were likely influenced by sympathy for Sharon.
Sharon fell ill Wednesday evening while he rested at his ranch in southern Israel ahead of a medical procedure scheduled for Thursday to close a small hole in his heart. Doctors rushed him to Hadassah Hospital, instead of a hospital in nearby Beersheba, because his condition did not appear dire, Sharon aides said. He suffered the bleeding stroke during the hourlong drive to Jerusalem.