Opponents of Prime Minister Ariel Sharon's (search) Gaza pullout said Tuesday they would keep trying to oust him and quash his peace efforts, a day after the Israeli premier narrowly survived a challenge to his leadership of the governing Likud Party (search).

The Israeli military pressed its offensive against Palestinian militants with airstrikes in Gaza (search) and arrests of 82 more militants in the West Bank (search).

Defense Minister Shaul Mofaz warned Israel would continue its pinpoint killings of militants, and said a Hamas leader's call for a halt to rocket attacks against Israel was inadequate. Hamas said the arrests were an attempt to weaken the Islamic militant group ahead of Palestinian national elections.

Sharon's 104-vote margin in the poll Monday by the 3,000-member Likud central committee was a slap in the face of party hard-liners who wanted to punish him for the Gaza pullout. The man who led the challenge, former Prime Minister Benjamin Netanyahu (search), said some committee members voted "under the pressure of the governing tyrant."

The ballot was ostensibly over a procedural issue: whether to hold elections for party leader in April, as scheduled, or move up the primary to November. But it was tantamount to a vote of confidence in the prime minister, who has expressed hopes the pullout will revive long-stalled peace talks that would ultimately lead to an independent Palestinian state.

Netanyahu, who wants to replace Sharon as prime minister, predicted he would prevail in the primaries by tapping the dissatisfaction of Likud members who think Sharon has betrayed the party's nationalist roots.

The close vote Monday demonstrated how bitterly divided the party remains, with many members opposed to Sharon's concessions to the Palestinians, he added.

"I expect to see this camp with all its force when it fights for the path of the Likud in the primaries and I have no doubt in the second phase we will win and the Likud will win," Netanyahu said.

Before the ballot, Sharon aides had suggested he would quit Likud if defeated and form a new party. Such a move could strengthen Israel's political center and improve chances of a Mideast peace deal because Sharon is popular with the public.

The prospect of a new party still loomed Tuesday because Sharon's victory was so slim. But his adviser Eyal Arad would not say whether the idea remained on the table.

As well as Netanyahu's challenge, Sharon is also facing pressure from his centrist Labor Party (search) coalition partners, who have threatened to quit and force elections before the November 2006 timetable if peace efforts stall.

Palestinian negotiator Saeb Erekat on Tuesday invited Sharon "to resume with us the permanent status negotiations so we can achieve our end game."

Renewed fighting with the Palestinians, just two weeks after Israel ended its 38-year occupation of Gaza, has compounded Sharon's problems. Hamas militants sent dozens of rockets raining down on southern Israel over the weekend, provoking a series of Israeli airstrikes that killed four militants and destroyed suspected weapons facilities throughout Gaza.

Early Tuesday, Israeli aircraft fired missiles at three roads in northern Gaza leading to staging areas for rocket attacks, the military said. Palestinian officials said one missile destroyed a bridge.

Israeli helicopters also fired two missiles in the town of Khan Younis in southern Gaza. Palestinian security officials said an office belonging to the ruling Fatah (search) movement and a money-changing store were hit. Israel said the money changer was a Hamas front.

Asked if Israel's defense policy included targeted killings, Mofaz told Army Radio it "includes everything the state of Israel knows how to do, and everything the defense establishment knows how to do, so...the (Israeli) residents of communities around Gaza will be able to live in peace and quiet."

Israel killed dozens of militants in targeted attacks during more than four years of violence, but suspended the practice for the most part following a February cease-fire with the Palestinians. Mofaz's statement was his first public acknowledgment that targeted killings were back in Israel's arsenal.

Mofaz also said an Israeli ground invasion of Gaza was possible, albeit as a last resort.

The Israeli defense minister scoffed at Hamas leader Mahmoud Zahar's (search) call to halt the rocket attacks.

"Mahmoud Zahar's words do not satisfy me," he said. Attacks by Hamas (search) proxies haven't stopped, and other militant leaders must also join the call, he said.

Israel has arrested hundreds of Palestinian militants in the West Bank as part of its operation against the militants. Overnight, 82 Hamas and Islamic Jihad (search) activists were rounded up in addition to 297 militants detained in the previous two days, the military said.

Hamas leaders accused Israel of targeting its political leaders, and said key candidates for Palestinian parliamentary elections in January were among those rounded up. Sharon has said he does not want Hamas to participate in the election unless the group disarms.

"Sharon doesn't want Hamas to reach the Palestinian parliament," said Hamas spokesman Mushir al-Masri. "He is using every possible means to block Hamas and push it aside."