Prime Minister Ariel Sharon won a decisive victory in Israel's election Tuesday, gaining an overwhelming endorsement for his harsh military crackdown on the Palestinian uprising and his tough response to terrorist attacks against Israeli civilians, according to official results reported this morning.

The outcome was a blunt repudiation of parties that advocate more conciliatory policies toward the Palestinians, particularly for Amram Mitzna, the Labor Party leader who campaigned on a platform of reopening long-stalled negotiations and withdrawing from the Gaza Strip and most of the West Bank.

The results could make U.S.-Israeli relations more difficult by hardening Israel's stand in U.S. and European efforts to revive peace talks and end the 28-month-old uprising in which more than 700 Israelis and 1,800 Palestinians have been killed. If the Labor Party and other centrist parties rebuff Sharon's efforts to build a national unity coalition, the prime minister is likely to seek a majority with smaller, ultra-nationalist and ultra-Orthodox parties, reinforcing opposition to a U.S.-endorsed peace plan calling for a halt to Jewish settlements in the West Bank and Gaza Strip and, eventually, a Palestinian state in the two occupied territories.

In a campaign that revolved around security, Sharon's Likud Party overcame concerns about Israel's floundering economy and a looming U.S. war against Iraq to claim a projected 37 seats, up from 19, in Israel's 120-member parliament, according to results reported from all polling stations. Mitzna and his Labor Party captured a projected 19 seats in the Knesset, down from 25.

"The parties that collapsed are the parties of Oslo -- those that supported concessions to the Palestinians," said Likud's hard-line minister for public security, Uzi Landau, referring to the 1993 Oslo peace agreement. "The national camp got a clear mandate. Peace and negotiations have to be based on uprooting terrorism. We will protect our security. That is the message."

Sharon led in opinion polls from the outset of the campaign, but he faltered several weeks ago after he and his sons got caught up in a corruption scandal that has dogged the Likud Party for about two months. While some polls showed Likud's lead over Labor dropping to as little as three seats following the reports, many supporters considered the corruption allegations to be part of a left-wing political vendetta and rallied behind Sharon. That, combined with underlying support for his tough security policies, helped Sharon bounce back even higher than expected.

The secular Shinui Party more than doubled its membership, to a projected 15 seats, by promising to push for cuts in state-sponsored benefits to Orthodox Jews. The ultra-Orthodox Shas party won 11 seats, a drop from 17, the results indicated. Meretz, one of Israel's clearest-cut peace parties, saw its membership sliced from 10 seats to a projected six. Its leader, Yossi Sarid, announced his resignation only minutes after the results of exit polls were made public .

The Israeli government reported election results by giving the percentage of the vote each party received, and said it would translate the outcome into parliamentary seats today. News agencies and television stations, basing their reports initially on exit polls and then on nearly complete results, projected how the parties will line up in the new parliament. The outcome could change slightly when ballots of diplomats and soldiers are counted.

Despite Sharon's resounding victory, the combination of a narrow coalition and the corruption charges that continue to hound him could jeopardize the stability of his second term, analysts said Tuesday.

"After the celebrations tonight, when he wakes up tomorrow morning, he's going to have a difficult job trying to put together a government," said Reuven Hazan, a Hebrew University professor. "He's going to need four or five other parties to get to 61 or more seats . . . and he's a prisoner to every one of his coalition partners."

But Tuesday night, the talk in Sharon's camp was of victory. "The people have had their say; they have decided in favor of my plan," Sharon said in a speech to a boisterous crowd of Likud supporters.

He continued, however, by making a strong appeal for national unity that was clearly aimed at Mitzna and Labor. "The differences between us are dwarfed by the murderous hatred of the terror organizations toward anything Israeli and Jewish, by the threat of war in the gulf and strikes against Israel, by the economic crisis that is ripping Israeli society apart," he said. "Israel needs unity. Israel needs stability."

In a concession speech before a small, listless crowd of supporters, Mitzna reiterated that Labor would no longer be a partner in Sharon's government, as it was during most of Sharon's current two-year term under the leadership of the former defense minister, Binyamin Ben-Eliezer.

"Sharon hopes that the Labor Party will once more serve as a fig leaf for his failing policy, but we do not intend to join him," Mitzna said. "The Labor Party under my leadership will remind Sharon and the entire public every day and everywhere that there is an alternative."

The tug of war over the next coalition started minutes after the exit poll results were announced.

"I appeal to the Labor Party that it must start by retracting its commitment not to join a unity government," said the leader of the Shinui Party, Yosef "Tommy" Lapid. "I say to Prime Minister Ariel Sharon, whom I congratulate: Sir, establish a secular unity government and we will serve in it faithfully."

While both Labor and Shinui have set conditions that make their membership in Sharon's government seem unlikely, some analysts have suggested that those are opening positions in a long bargaining process. After an election, parties typically form negotiating teams that bargain over cabinet positions, government guidelines, state funding for pet organizations and other matters, then decide whether to join based on the spoils they would receive.

If he cannot persuade the more centrist parties to change their position, Sharon may be led to form a narrower government with ultra-nationalist and Orthodox parties. Many of their members hold positions that could pull Sharon toward an even more uncompromising approach in dealing with the Palestinians. Some of the parties, for instance, oppose an independent Palestinian state on principle and reject even more clearly than Sharon the idea of abandoning Jewish settlements in the West Bank and Gaza Strip.

Tuesday's election had the lowest voter turnout in Israeli history, with only 68.5 percent of those eligible casting ballots. The turnout reflected what opinion polls and interviews with voters have shown for weeks: A large percentage of Israel's 4.7 million potential voters were disenchanted with all their choices after 28 months of clashes with the Palestinians and a badly slumping economy. Even those who turned out to vote for one of the 27 parties vying for positions in the parliament showed little enthusiasm.

"I'm discouraged. I don't have any hope that things will be better for us in the next few years," said Ilanit Cohen, a 33-year-old mother of two who recently closed her boutique for lack of business and whose husband has been laid off from his factory job. "But at least Sharon is strong, at least he won't give in to the Palestinians."

The election was conducted under stringent security precautions, with an estimated 30,000 police officers, soldiers and guards patrolling polling booths, city streets and public areas. Palestinians were banned from traveling out of the West Bank or Gaza Strip until this morning. Highway and border checkpoints were increased in an effort to reduce the chances of an attack such as the one that occurred in November during Likud's primary election, when two Palestinian gunmen opened fire on a polling station in northern Israel, killing six people.

Researchers Samuel Sockol and Eetta Prince-Gibson contributed to this report.

An Israeli police officer checks a car in central Jerusalem as part of heightened security measures for the election.