Prime Minister Ariel Sharon (search) narrowly fended off a challenge within his own party Monday in a vote widely seen as a referendum on his leadership following the contentious withdrawal from the Gaza Strip (search).

Members of the right-wing Likud Party (search) voted 1,433 to 1,329 — a margin of 104 votes — against a proposal by Sharon's opponents to move up the date of party primaries to November. The results, announced by the party, mean the primary will be held on schedule next spring, as Sharon wanted.

The vote, which Sharon won 52 percent to 48 percent, was seen as a referendum on his leadership of Likud, the party Sharon helped found more than three decades ago. Led by his main rival, Benjamin Netanyahu (search), party hard-liners have accused Sharon of abandoning the Likud's nationalist roots by withdrawing from Gaza.

Netanyahu, who had wanted an early primary to capitalize on anger over the Gaza withdrawal, conceded defeat but said Sharon cannot ignore the strong opposition against him within the party. Despite the setback, Netanyahu said he still planned to run in next spring's primary in an effort to oust Sharon.

"We lost by a very few votes. There is a very large camp that went against the flow, against the wind, against the pressure, against the leadership and against the temptations," said Netanyahu, a former prime minister.

Polls in recent weeks had shown Netanyahu with double-digit support among Likud voters, and a recent barrage of rockets launched at Israel by Palestinian militants had been expected to further bolster Sharon's opponents. Netanyahu has repeatedly warned the Gaza pullout would encourage Palestinian violence.

In response to the rocket attacks, Israel launched a wide-ranging offensive against militants across Gaza and the West Bank over the weekend.

Early Monday, Israeli aircraft attacked suspected weapons factories around Gaza City as well as the southern Gaza towns of Rafah and Khan Younis. The airstrikes knocked out power to the eastern part of Gaza City and caused damage to several buildings, but no injuries were reported.

The army said its targets included an access road leading to a rocket-launching site in northern Gaza, weapons-manufacturing factories and storage facilities belonging to militant groups.

Later Monday, aircraft fired missiles at an empty field militants used to launch rockets at Israel, a strike meant to deter further attacks, the military said.

Israel pressed ahead with its air campaign despite Hamas leader Mahmoud Zahar's call on militants to end the rocket attacks. Zahar said Hamas remained committed to a seven-month-old cease-fire and he wanted to prevent further Israeli attacks.

Even if Hamas stops its rocket attacks, it remained unclear whether smaller militant groups would follow suit. Islamic Jihad said it would not observe the truce after an Israeli airstrike Sunday killed one of its top commanders in Gaza.

Israeli security officials said they would wait to see whether the Palestinian attacks would end before calling off the offensive. On Monday afternoon, militants launched a mortar shell at an Israeli community north of Gaza, causing no injuries or damage, the army said.

"I hope that members of the party will come to vote against this proposal, which will badly harm the Likud," a smiling Sharon said as he cast his ballot Monday afternoon.

Sharon's allies had said a loss in the vote would make him a lame-duck prime minister and might push him to resign from the increasingly hawkish party and form a new centrist party, which he would lead into general elections.

Recent polls show a new party led by Sharon would sweep elections, winning more than twice the seats of a Netanyahu-led Likud.

As head of Likud, Sharon has had to fight against hard-line lawmakers in the party to implement his policies, and rebellious Likud parliamentarians repeatedly tried to bring down his government to stop the Gaza withdrawal.

Late Sunday, Sharon was thwarted from addressing a party convention when his microphone cut out twice. Likud officials said the sound system had been sabotaged. After waiting nearly half an hour, Sharon left the hall without speaking.