Updated

A scan of Ariel Sharon's brain on Sunday showed improvement, but doctors decided to wait another day to start bringing the Israeli leader out of his medically induced coma, an important step in determining how much damage he suffered from a massive stroke.

One of Sharon's doctors said if the prime minister survives, he would not be able to return to office. Acting Prime Minister Ehud Olmert told the Cabinet he would work to carry on Sharon's political legacy.

Sharon remained in critical condition Sunday at Jerusalem's Hadassah Hospital after suffering a stroke late Wednesday and undergoing two lengthy surgeries to stop massive bleeding in his brain. Sharon previously experienced a mild stroke Dec. 18.

Doctors have kept Sharon in a medically induced coma and on a respirator since Thursday to give him time to heal. Sharon's medical team decided that on Monday morning they would begin reducing the level of sedatives he is receiving to start pulling him out of the coma.

Experts said the process could take six to eight hours, and doctors should have a good idea of the extent of the damage by the end of the day.

A new brain scan Sunday showed his vital signs, including the pressure inside his skull, were normal, said Dr. Shlomo Mor-Yosef, the hospital director.

"His condition is still critical but stable, and there is improvement in the CT picture of the brain," Mor-Yosef said.

"In light of all these factors, the panel of experts decided to start the process of taking him out of the sedation tomorrow morning. This all depends, of course, on whether the prime minister makes it until tomorrow morning without any significant incidents."

Doctors had planned to start pulling Sharon from the coma Sunday, but decided to wait another day after performing the new scan.

The 77-year-old Sharon, Israel's most popular politician, was seen by many here as the best hope for resolving the Israel-Palestinian conflict. His grave illness, just three months before elections, has stunned Israelis and left Middle East politics in limbo.

Doctors will pass their assessment of brain damage to Attorney General Meni Mazuz.

"They will inform us the moment they wake him up from the sedation and they will know what systems were damaged and what his situation is," Justice Ministry spokesman Jacob Galanti said.

If doctors determine that Sharon is permanently incapacitated, the Cabinet would meet immediately to choose a new prime minister from the five sitting Cabinet ministers from Sharon's Kadima Party who also are lawmakers.

Olmert is seen as Sharon's potential heir.

One of Sharon's surgeons, Dr. Jose Cohen, said that while the premier's chances of survival were high, his ability to think and reason would be impaired.

"He will not continue to be prime minister, but maybe he will be able to understand and to speak," the Argentina-born Cohen said in comments published Sunday by The Jerusalem Post.

Outside experts were even less optimistic.

"There is zero expectation on my part that he will have the capacity to perform in any kind of formal way," said Dr. Keith Siller, Medical Director at the NYU Comprehensive Stroke Care Center.

"We are basically hoping he survives and that he has some kind of ability to get some rehab so he can have some useful function again. But we are talking about the basics, we are talking very basic things. The complexity of this man, and what he did for a living, this is not to even be considered now. This is absolutely unrealistic at this time."

Israel's Cabinet met for its weekly gathering Sunday for the first time since Sharon's stroke.

Olmert sat next to Sharon's empty chair, the prime minister's untouched gavel rested in the middle of the table.

Olmert told the ministers that Sharon would want everyone to get back to work on the country's pressing security, social and economic issues.

"This we will continue to do," he said. "We will continue also to carry out the wishes of Sharon, to manage affairs as necessary."

The Cabinet meeting was Olmert's first formal opportunity to persuade Israelis and the world that the nation's affairs were in good hands and that he would pursue Sharon's political program.

Shimon Peres, the Labor Party elder statesman and Nobel Peace Prize laureate who abandoned his party to join Sharon in Kadima, dispelled rumors that he might return to his former party or challenge Olmert. Addressing a gathering in Jerusalem on Sunday, he said he "fully and faithfully" supports Olmert. Later, in a CNN interview, he called on his backers to vote for Kadima.

Speaking to reporters later, Olmert expressed hope Sharon would get better.

"I pray with all the people of Israel that my tenure as acting prime minister will be short, so soon enough we will be able to see again the leader of Israel," he said.

Before his collapse, Sharon appeared headed to a landslide victory in March 28 elections as head of his new centrist Kadima Party, formed in the wake of his withdrawal from Gaza this summer. Sharon was expected in a third term to try to draw Israel's permanent boundaries, evacuating small West Bank settlements while strengthening Israel's hold over larger ones.

But it is unclear whether Olmert or any other successor would have the popularity or charisma to carry out such a plan.

Sharon had been reluctant to resume long-stalled peace talks, saying the Palestinians were not a trustworthy partner.

In the West Bank, Palestinian Prime Minister Ahmed Qureia wished Sharon a quick recovery and expressed hope for new peace talks.

"We are looking for a new era in which we can negotiate and be partners in a real peace that serves both peoples," he told his Cabinet.