UNITED NATIONS – Acting Prime Minister Olmert took the reins of power in Jerusalem yesterday as Prime Minister Sharon lay unconscious in Hadassah Hospital’s intensive care unit. And although Israeli politicians vowed to freeze the race for Israel’s leadership out of reverence to their ailing leader, they were jockeying for position nevertheless.

Most political observers, as well as national polls, had predicted an easy re-election for Mr. Sharon before his health took a significant downturn Wednesday night. Yesterday, a genuine three-party race began to emerge.

“This is a new game with new rules,” Israel Radio’s top political analyst, Hanan Crystal, told The New York Sun, with Benjamin Netanyahu of the right-wing Likud Party, Amir Peretz of the leftist Labor, and Mr. Olmert of the recently formed centrist Kadima as front-runners in the March 28 election.

Mr. Olmert, a veteran of Israel’s political battles, yesterday presided over his first Cabinet meeting since Mr. Sharon’s hospitalization. Occupying his customary vice premier seat around the oval Cabinet table, Mr. Olmert left the place reserved for the prime minister empty, in a gesture meant to signify the nation’s hope for Mr. Sharon’s recovery. Mr. Olmert also worked out of his Jerusalem Ministry of Industry, Trade, and Labor office, rather than the more spacious prime minister’s office.

In a meeting expected to carry tremendous political significance, Mr. Olmert is scheduled to speak with a former prime minister, Shimon Peres, on Friday morning. The two will “update and consult” with each other, Mr. Peres’s longtime aide, Yoram Dori, told the Sun, indicating that Mr. Olmert, who has never been prime minister, intends to draw on Mr. Peres’s experience as a party and national leader. Publicly, the two are expected to express respect for Mr. Sharon as well as hope for his recovery.

Spokesmen at Hadassah Hospital, where Mr. Sharon lay in a coma-like state after seven hours of brain surgery to drain cerebral hemorrhaging, shied away from predicting how long the prime minister would be incapacitated, and defined his condition as “grave but stable.” He is expected to have an MRI on Friday.

“We are fighting for the life of the prime minister, with no compromise,” Hadassah’s director, Dr. Shlomo Mor-Yosef, said, dispelling reports the prime minister has already died. He said the 77-year-old Mr. Sharon will remain unconscious, breathing with the aide of a ventilator, until at least Sunday. The doctor urged patience.

Mr. Sharon, who is not expected to return to full political activity, only recently began forming his Kadima Party, and the party has yet to present a candidate list and political platform for the next Knesset.

“It is now a Gaullist party without De Gaulle,” Mr. Crystal said. The biggest concern of its leaders is that those who left Likud and Labor and joined Kadima, hoping to ride on Mr. Sharon’s coattails, could be wooed back to their old parties. Mr. Olmert will have to consolidate quickly his leadership and demonstrating that he is a vote-getter, able to retain the nearly 40% of Israelis who are seen as holding centrist positions, according to Mr. Crystal.

Some of Mr. Olmert’s political skills, honed during his years as a Likud party insider and as mayor of Jerusalem, were on view yesterday as one Kadima member, Meir Sheetrit, reversed his call to challenge Mr. Olmert’s leadership.

Support also was expressed by the top female vote-getter in the party, Tzipi Livni, as well as by the defense minister, Shaul Mofaz. All are Likud members, and although long-time Labor supporter Haim Ramon is fully in Mr. Olmert’s corner, the vice premier needs Mr. Peres’s credentials to attract centrist voters, Mr. Crystal said.

According to a poll published yesterday by Ha’aretz, a Kadima headed by Mr. Peres would win 42 seats in the 120-member Knesset, while under Mr. Olmert’s leadership it would win 40.

Mr. Peres famously has never won a race for prime minister and is not expected to vie for the leadership again. He pledged his support for Kadima mostly because of Mr. Sharon’s involvement, but has not joined the party officially. He left Labor in the wake of his loss to Mr. Peretz in the November primary vote.

Now Mr. Peretz, too, is expected to ask for Mr. Peres’s blessing. Yesterday Mr. Peretz reportedly told Labor activists to cease all campaign activity until further notice out of respect for Mr. Sharon. On the right, Mr. Netanyahu yesterday announced that four Likud Cabinet ministers will remain in the government to avoid political instability.

President Ahmadinejad of Iran was quoted by the Iranian Students News Agency as saying he hopes for Mr. Sharon’s death, the Associated Press reported. “Hopefully, the news that the criminal of Sabra and Chatilla has joined his ancestors is final,” he said, according to the AP.

Although several Palestinian Arabs celebrated in Gaza, Palestinian leader Mahmoud Abbas said yesterday, “We are watching with great worry at what might happen if [Mr. Sharon] is harmed.” He added that the January 25 Palestinian parliamentary election will not be postponed.

In America, the televangelist Pat Robertson said on the air, “God has enmity against those who, quote, ‘divide my land.'” Referring to Mr. Sharon’s decision to withdraw from Gaza, he added, “Woe unto any prime minister of Israel who takes a similar course to appease the E.U., the United Nations, or the United States of America. God says, ‘This land belongs to me. You better leave it alone.’ “The Anti-Defamation League expressed its “shock and outrage” at Mr. Robertson’s statements.

Secretary of State Rice called Mr. Sharon “a man of courage.” Her and the White House’s support for Mr. Sharon, which has sustained the prime minister’s political popularity in the past five years, is expected to be transferred now to Mr. Olmert. “Just imagine his picture next to Bush,” Mr. Crystal said. “That will definitely boost Olmert’s leadership credentials.”