With Israel and Hamas both claiming victory in the Gaza Strip, there is one clear loser: the U.S.-backed Palestinian Authority, which desperately wants a peace accord with Israel and a unified Palestine in Gaza and the West Bank.

Israel's 22-day assault on Hamas-ruled Gaza made the West Bank-based Palestinian Authority look ineffective and marginalized, unable to stop the carnage. Popular support for its peace talks with Israel, already declining, now seems weaker than ever.

And a tentative cease-fire that left Hamas still in charge of Gaza threatens to reinforce the rift between the Palestinian territories, further setting back hopes for a settlement of the decades-old Middle East conflict.

At an Arab summit in Kuwait on Monday, Palestinian Authority President Mahmoud Abbas pleaded for a revival of the power-sharing arrangement that broke apart in 2007 when Hamas, an armed Islamist movement, ousted his secular Fatah forces from Gaza in a ruthless factional fight.

He called for immediate talks between the two factions to form a "unity government" to rebuild the war-devastated territory, organize elections and negotiate peace with Israel.

Salam Fayyad, Abbas' prime minister, echoed the appeal at a news conference in the West Bank city of Ramallah. The urgency in both men's voices signaled a position of weakness, reflecting the frustration of Western-oriented Palestinians over the outcome in Gaza.

Fayyad said he worried that reconstruction aid, including $1 billion pledged Monday by Saudi Arabia, would strengthen Hamas and its message of violent confrontation with the Jewish state. He urged international donors to funnel aid through the Palestinian Authority, with the aim of forcing Hamas to agree to a reconciliation that might moderate its policies.

If the division of Palestine were to become "internationally acceptable," he warned, "this would endanger the Palestinian cause."

But the authority has no means to reassert its presence in Gaza without the consent of Hamas. And although Hamas said it was open to a new power-sharing deal, it seemed in no hurry to strike one with Abbas, whom one Hamas official dismissed as "a full partner" in the Israeli assault.

"Hamas will be much less powerful militarily against Israel but significantly stronger against Fatah," said Ghassan Khatib, an independent Palestinian analyst in Ramallah. "No one will challenge its control of Gaza. It is in much less need of a unity government."

As a result, Barack Obama's administration will face the same Middle East conundrum that stymied President Bush's belated effort to forge a deal on Palestinian statehood: Israel is reluctant to give Abbas a state as long as he cannot enforce peace in Gaza, much less enter the territory.

Calculated blow

West Bank leaders view Israel's offensive in Gaza as more than an act of self-defense against years of Hamas rocket fire into southern Israel. They see it as a calculated blow to the Israeli-Palestinian peace talks Bush initiated in late 2007 over the divisive issues of borders, Palestinian refugees and control of Jerusalem.

"The Israelis wanted to weaken Hamas enough to make it less of a threat to their country but still allow it to control Gaza," said Samir Abdullah, the Palestinian Authority minister of planning. "By enhancing Palestinian division, Israel can claim that there is no reliable partner for a final peace settlement."

Mark Regev, an Israeli government spokesman, said Israel was interested in advancing the peace talks. He said Israel had scored a military success over Hamas that is likely to lead to "more flexibility" in its security restrictions on the West Bank and improve the climate for negotiations.

But Israel's assault has undermined Palestinian support for Abbas and his peace agenda. Many West Bank residents, even those who oppose Hamas' violent ideology, considered the Gaza offensive an attack on all Palestinians and accused Abbas of not doing enough to stop the killing of more than 1,300 Gazans.

Abbas misread public opinion by declaring that Hamas was partly to blame. His own police forces used clubs and tear gas to put down West Bank street protests against Gaza bloodshed whenever participants chanted Hamas slogans or unfurled the Hamas flag.

"The people are going to hold accountable whoever failed to stand by our people in Gaza," said Izzeddin Ibrahim, a 25-year-old engineer in Ramallah. "There is no chance left to make peace with those who kill our people. We cannot accept anyone meeting with Israelis anymore."

Such criticism also comes from within Abbas' Fatah movement, which had led every major Palestinian battle against Israel since its founding by the late Yasser Arafat in the late 1950s. By sitting this one out, senior Fatah members acknowledge, the movement has lost respect.

"Those who fight the occupation gained popularity, and we who stood back and watched lost," said Kadura Fares, a member of Fatah's revolutionary council. "We are no longer in the vanguard."

Khalil Shikaki, director of the Palestinian Center for Policy and Survey Research and a sometime advisor to Abbas, said that during the Israeli offensive there was a shift in public opinion in favor of Hamas. But he said it was probably temporary and would not threaten Abbas' position in his own movement.

But he said a large majority of Palestinians, as many as eight in 10, believe Abbas' peace talks with Israel are pointless and should be halted.

The U.S.-brokered talks are on hold, awaiting the outcome of Israel's Feb. 10 elections and a signal of the Obama administration's approach to the conflict.

Nabil abu Rudaineh, Abbas' spokesman, said the Palestinian leader would urge Obama to abandon the Bush administration's policy of trying to isolate Hamas. He said U.S. support for a power-sharing deal could help coax the Islamic group to support peace talks with Israel.

Animosity runs high

Hamas officials have said they would allow Abbas' police officers into Gaza to control border crossings with Egypt and Israel, a condition both countries have set for ending their blockade of the territory.

But Hamas is reluctant to make other concessions and has challenged Abbas' authority to continue as president because his four-year term technically ended Jan. 9. In Gaza, animosity between the rival factions runs high; Israeli officials say Hamas killed 70 Fatah supporters during the offensive, accusing them of collaborating with Israel.

Aluf Benn, editor at large of Israel's Haaretz newspaper, said the Obama administration has an opportunity to influence Hamas.

"A stable cease-fire can serve as a basis for engaging Hamas and trying to lure it into accepting, even ambiguously, the international terms for recognition" -- acceptance of Israel's right to exist, he said. "If Israel is ready to live with Hamas, so can the United States."

boudreaux@latimes.com

Special correspondent Maher Abukhater contributed to this report.