JERUSALEM — The stroke that left Israeli Prime Minister Ariel Sharon hospitalized has abruptly recast the nation's election campaign and raised questions about whether the mass of centrist voters he hoped to mobilize under a new party would hold together behind a replacement leader.
The seriousness of Sharon's condition Thursday made it appear unlikely he could continue serving as prime minister and lead his new movement, Kadima, or Forward, in elections still scheduled for March 28.
Analysts said Sharon's departure from the election scene could threaten the effort to create an alternative for Israeli moderates who have grown disenchanted with past peace efforts but who nonetheless support practical steps to reduce tensions with the Palestinians, even if they fall short of a negotiated agreement. Most Israelis, for example, backed Israel's unilateral pullout from the Gaza Strip and a portion of the West Bank last summer despite fierce opposition from the right wing.
As the party laying claim to those voters, Kadima has led most polls by a wide margin since Sharon created it in November, but his absence is likely to make the race more of an even three-way matchup involving the left-leaning Labor Party and the conservative Likud Party. Now some former Labor and Likud members who flocked to Sharon's banner may find their way back to their previous parties.
"Everything's up in the air," said Gadi Wolfsfeld, a professor of political science and communications at Hebrew University in Jerusalem. "Everything's a jumble."
The figure most likely to benefit is former Prime Minister Benjamin Netanyahu, Sharon's longtime rival and the Likud's new leader. Netanyahu resigned from the Sharon government to protest the Gaza pullout and has ruled out making the kind of territorial concessions the prime minister has said are necessary to establish viable long-term borders for Israel, with or without a peace deal.
Netanyahu is now in a better position to woo back some of the former Likud supporters who were drawn to Kadima by the force of Sharon's personality.
"Netanyahu now will have a chance to take advantage of this situation," said Orit Galili, a political science professor at Tel Aviv University.
In forming a new party, Sharon hoped to capitalize on what analysts say is a hefty percentage of voters who have lost faith in the Likud and Labor and accept his argument that Israel will be more secure if it cedes control over some areas it captured in the 1967 Middle East War.
Although Kadima's agenda has not been spelled out in detail and its leadership represents an odd amalgam from the center, right and left, the public's appetite for a pragmatic path remains a factor in the race, even if Sharon does not, analysts said.
"It's based around Sharon, but it's also based around a pragmatic middle that the Israeli public wants to see in leadership," Galili said.
For now, the vehicle for these voters is Kadima, though the depth of its support has yet to be tested. As an impromptu movement still without formal organization, the party will probably have to convince supporters that it is more than a one-man show.
Critics have described Kadima as a kind of Rorschach test that allows voters to read in its rough contours the political program of their choosing. At its center was Sharon; in a recent poll of Kadima supporters, half said he was their main reason for backing the party.
The near-term future of the party will hinge on whether it arrives smoothly at a replacement leader and then succeeds in playing up the Sharon legacy, analysts said. Vice Premier Ehud Olmert, a Sharon confidant and acting prime minister, is the most likely heir within Kadima but could face a damaging battle for party leadership.
Kadima "has a future if they do not fight with each other, if they stick with Sharon's ideology and present themselves as the children of Sharon," said Mina Zemach, an Israeli pollster.
Some analysts said Olmert's political future could depend on how well he performs as stand-in prime minister in coming weeks before the elections -- plenty of time, commentators said, to win or lose public favor.
For example, Olmert could suffer if Palestinian militants carry out a wave of attacks and he is seen as not responding forcefully enough. Shimon Peres, the former Labor leader who took over as prime minister after the assassination of Yitzhak Rabin in 1995, lost to Netanyahu several months later after a series of suicide bombings.
In some ways, Netanyahu finds himself in a similar position now, with the chance to capitalize on a suddenly altered political landscape and on any public disappointment with a substitute national leader.
Netanyahu is a gifted campaigner and more charismatic than Olmert, and Israeli politics today increasingly revolves around personality, Galili said. But other analysts noted that Netanyahu was a polarizing figure and that his tenure as prime minister from 1996 to 1999 alienated many voters.