Prime Minister Ariel Sharon's hawkish Likud Party appeared headed for a convincing victory in elections Tuesday, but the urgent challenges of forming a stable government amid the turmoil of the Palestinian uprising will give him little time to savor victory.

In ongoing violence, five Palestinians were killed. Three died in a powerful explosion at a Gaza City house. Palestinians claimed an Israeli helicopter fired a missile. But the army said no helicopter was in the area, and military sources said the blast was caused by the premature explosion of a bomb being assembled by militants.

In the West Bank, Israeli troops shot dead a Palestinian gunman and a stonethrowing youth in Jenin, Palestinian witnesses said. The army said soldiers fired on armed men, but offered no information on Palestinian casualties.

Sharon's party was far ahead in the opinion polls, and the ballot, which will fill parliament's 120 seats and determine the next prime minister, may be short on drama.

But as soon as the polls close Tuesday night, the horse trading begins, and Sharon could face great difficulties in establishing the durable, broad-based government that he seeks to steer Israel through this period of crisis.

The vote is Israel's fourth national election in seven years. With many Israelis feeling drained by the 28 months of fighting with the Palestinians, the campaign has inspired little passion, though Sharon and his main rival, Labor Party leader Amram Mitzna, have offered sharply different approaches to the confrontation.

"I hope this will be the last time we will have elections in the next four years," Sharon said as he cast his ballot at a Jerusalem high school. No Israeli government has served a full four-year term since 1988, and Sharon's outgoing coalition survived less than two years.

Mitzna, who voted in the coastal city of Haifa where he has served as mayor, said that many "hungry people and people without work are going to polling stations. And we hope that we will embark on a new path."

Sharon has kept Israeli troops in Palestinian cities and towns for months, saying they will remain until Palestinian attacks have been stopped and the militants crushed. The dovish Mitzna party champions a quick withdrawal of Israeli soldiers and settlers from the Gaza Strip and much of the West Bank.

"No one really expects the dawn of a new day, at most the twilight of an old evening," commentator Hemi Shalev wrote in the Maariv daily.

About 4.7 million of Israel's 6.6 million residents are eligible to vote, with 27 parties competing. The polls close at 10 p.m. (3 p.m. EST). Immediately afterward, Israeli TV stations planned to broadcast exit polls and telephone surveys. Complete, though unofficial, results were expected Wednesday morning.

At 10 a.m., three hours after the polls opened, only 10.2 percent of eligible voters had cast ballots, according to Avi Diskin of the Central Election Committee. He said it was the lowest turnout ever in Israel at this stage of an election, though the polls were to remain open for another 12 hours.

To guard against possible attacks, Israel has clamped a three-day closure on the West Bank and the Gaza Strip, which will keep Palestinians from entering Israel proper.

With Sharon's Likud expected to emerge as the largest faction — Monday's opinion polls had the right-wing party taking 30 to 33 seats — attention is already shifting to post-election coalition troubles that could significantly weaken the prime minister.

Mitzna has rebuffed Sharon's appeals to bring the left-leaning Labor Party into another Likud-led government. "A promise is a promise," Mitzna said Monday, reaffirming his pledge not to renew Labor's alliance with Sharon.

Without Labor, Sharon, 74, would have to form a coalition of right-wing and religious parties. Polls predict such a lineup will have a narrow majority in parliament, but would be inherently unstable, leaving the government vulnerable to collapse. Such a grouping would also lead to demands for even tougher security measures against the Palestinians.

A wild card in the election is Shinui, an avowedly secular party that strongly opposes special privileges accorded the ultra-Orthodox. Shinui is forecast to go from its current six seats to 15 or more, and would likely become the third largest party.

The Palestinians closely watched the Israeli campaign, and appeared resigned to another victory for Sharon, who won the prime minister's post in a special election in February 2001.

"I think all indications are that things will get worse," said Palestinian Cabinet minister Saeb Erekat said. "I don't see any sign of reviving hope or reviving the peace process."