Acting Prime Minister Ehud Olmert took decisive hold of the country's reins Thursday as Prime Minister Ariel Sharon continued to fight for his life. Hadassah Medical Organization director-general Shlomo Mor-Yosef told reporters Thursday evening that the 77-year-old Sharon's condition was "serious, but stable." He said that Sharon would be under a general anesthetic and on a respirator for 24 to 72 hours. Mor-Yosef said his vital signs - including blood pressure, pulse rate and intercranial pressure - were within the normal range. In the meantime, Olmert and the Prime Minister's Office took pains to broadcast a "business as usual" atmosphere, keen on sending out a message to both Israelis and the rest of the world that the government was functioning in an orderly manner. One senior official in the Prime Minister's Office said that messages were sent to Hizbullah and "terrorist organizations in the south" not to use this period to "try to test Israel." Olmert received security updates before convening an emergency cabinet meeting at 9 a.m., and received a security briefing in the afternoon from Defense Minister Shaul Mofaz and a diplomatic briefing from Foreign Minister Silvan Shalom. Sharon underwent surgery at around midnight Wednesday at Hadassah University Medical Center at Ein Kerem that lasted for some eight hours. He was transferred to the neurosurgery intensive care unit following the operation which, while it succeeded in stopping his cerebral hemorrhaging, left him in serious condition with grave questions of whether he would survive, and if so at what capacity. Mor-Yosef said that the extent of the damage to Sharon's motor and cognitive skills would only be known as he was gradually taken off the anesthesia. "The central treatment that the prime minister is receiving is a deep anesthesia and ventilation," he said. "The aim of this treatment is to reduce the intercranial pressure, the pressure inside the brain and blood pressure to enable the brain to recover from the trauma of the stroke and the operation." Mor-Yosef stressed that this treatment would take 24 to 72 hours, and that at this stage the doctors were simply monitoring Sharon's vital signs. He did say that Sharon's pupils were reacting to outside stimuli, but that since he was under a general anesthetic, it was impossible yet to determine what damage was caused to his brain or body. Mor-Yosef would not speculate on the chances of recovery. He also defended a controversial decision taken Wednesday evening, when Sharon first felt ill, to drive him to the hospital in Jerusalem rather than to the closer Soroka Hospital in Beersheba. The medical update Thursday evening was one of several that Mor-Yosef gave throughout the day. He said in the afternoon that he wanted to "balance the rumor mill that is flooding the country. As the director-general of Hadassah, I commit myself to putting out announcements whenever there is any change in the prime minister's condition." Throughout the day there were rumors that Sharon had passed away. Olmert convened the emergency cabinet session the first thing in the morning, sitting in his usual chair next to that of the prime minister. According to a senior official in the Prime Minister's Office, he wanted to present a picture of governmental continuity and unity in the face of the current crisis. The Prime Minister's Office issued a statement saying that Olmert would convene the weekly cabinet meeting on Sunday as usual. "This is a difficult and unusual situation," Olmert told the cabinet. "The resilient State of Israel will know how to deal with it." Olmert told the ministers that he had been in constant contact with Sharon's staff and the hospital through the long night and had also received the "necessary security updates." "On behalf of all ministers, I embrace Gilad and Omri, Arik's beloved sons, and pray with them for their father's recovery," Olmert said. "Arik is not only prime minister and a leader but is the good friend of all of us. This is a difficult time and we - all of us - will be up to the task." Prime Minister Office's Director-General Ilan Cohen said after the meeting that "our message is that we are a modern, orderly country that will continue to function despite the difficult situation." Attorney-General Menahem Mazuz briefed the ministers on the legal situation created by Sharon's incapacitation. He told the ministers that Sharon was temporarily incapacitated and that - in accordance with the Basic Law: Government - his powers and prerogatives had been transferred to Acting Prime Minister Olmert. Mazuz added that should there be further deterioration in Sharon's condition and the doctors conclude that he was permanently incapacitated, or should he die, the cabinet would have to choose an interim prime minister from among the Kadima ministers who are also MKs. Mazuz also indicated to the ministers that the Knesset elections set for March 28 by presidential order would be held as scheduled. President Moshe Katsav has also urged the Knesset to hold the elections on that day. The Basic Law: Government clause governing succession of the prime minister could set the stage for a free-for-all among Kadima leaders as to who takes over the post of interim prime minister, assuming that Sharon does not recover from the stroke. If Sharon dies or is deemed permanently incapacitated between now and the election, Olmert would lose the constitutional edge he currently enjoys over his Kadima rivals for party leadership. According to the law, in the case of Sharon's permanent incapacitation or death, the cabinet would choose a minister who was also an MK and belongs to Sharon's faction to temporarily take over as head of government. Among the leading candidates to challenge Olmert would be Justice Minister Tzipi Livni and Transportation Minister Meir Sheetrit. Defense Minister Mofaz would not be a contender because he is not a serving MK. The Kadima MKs, however, made clear that at this time the party's leadership was not foremost on their minds. Livni emerged from the cabinet saying that she would do everything she could to assist Olmert at this time. Similar sentiments were also articulated by Sheetrit. Olmert was in contact during the day with numerous opposition MKs, updating them on Sharon's condition and the present government situation. He is scheduled to meet Shimon Peres on Friday. In addition, Olmert spoke by phone with Palestinian Authority Chairman Mahmoud Abbas, who phoned to express concern about Sharon's condition. Abbas, according to the Prime Minister's Office, wished Sharon a full recovery, and said that he was following with "great concern" the reports from the hospital. Olmert thanked Abbas for the call, and said that Sharon told him he was interested in moving the diplomatic process with the Palestinians forward. Earlier in the day chief PA negotiator Saeb Erekat reacted to Sharon's condition by saying, "We are all human beings and we are all sorry about Sharon's demise... We will of course negotiate with whoever leads Israel. "We don't try to tell them who should lead their negotiations. Of course, we don't interfere in internal Israeli politics, but the fact is that if someone sneezes inside Israel, we Palestinians immediately catch a cold." Erekat said that the PA elections would be held as scheduled at the end of this month "provided that Olmert was not so foolish as to prevent Palestinians from voting in east Jerusalem." Delaying the elections would only make Hamas stronger, he said. Olmert also spoke by phone with South African President Thabo Mbeki who called to express his concern, and that of his country. Indeed, throughout the day goodwill calls and statements poured in from all over the world, ironic considering the degree to which Sharon was once castigated around the world. US President George W. Bush, who developed a close working relationship with Sharon over the last five years, issued a written statement that "Laura and I share the concerns of the Israeli people about Prime Minister Ariel Sharon's health, and we are praying for his recovery." Secretary of State Condoleezza Rice termed Sharon "a man of enormous courage." British Prime Minister Tony Blair issued a statement saying that he was "deeply concerned by the news and has passed a personal message of goodwill to him and his family." British Foreign Secretary Jack Straw called Sharon "a towering figure, not only in Israel but in the whole of the region." French President Jacques Chirac, German Chancellor Angela Merkel and Russian President Vladimir Putin all sent good wishes to Sharon, as did Italian Premier Silvio Berlusconi. Japan's Prime Minister Junichiro Koizumi, who was scheduled to meet Sharon on Monday, postponed his visit, as did senior US envoys Elliott Abrams and David Welch, who were scheduled to arrive Thursday for talks with Israeli and PA officials about the upcoming PA elections. Abrams, the deputy national security adviser, heard that Sharon had suffered a stroke when he was at the airport ready to board a flight to Israel, and decided to postpone his visit. Dan Izenberg contributed to this report.