JERUSALEM —Israel's leader, having failed to block the Palestinians from taking their quest for a state to the U.N., defiantly declared Thursday that they would have to back down from long-held positions if they ever hope to gain independence.

Ahead of Thursday's vote, thousands of Palestinians from rival factions celebrated in the streets of the West Bank. In a departure from its previous opposition, the Hamas rulers of the Gaza Strip said they would not interfere with the U.N. bid, and its supporters joined some of the celebrations.

Western-backed Palestinian President Mahmoud Abbas turned to the United Nations after four years of deadlock in Mideast peace efforts. While the initiative, all but certain to pass, will not immediately bring about independence, Palestinians hope the strong international endorsement will give them more leverage in future negotiations with Israel.

Speaking to reporters in New York, Abbas said diplomatic pressure to abandon the initiative was "tremendous," but that he would not be deterred.

"We said our word, and the vote will take place," he said.

The resolution calls for a Palestinian state in the West Bank, Gaza and east Jerusalem, territories Israel captured in the 1967 Mideast war. Israeli Prime Minister Benjamin Netanyahu has rejected a pullback to the 1967 lines, saying it would threaten Israeli security. Israeli settlements in the West Bank and east Jerusalem are now home to some 500,000 Israelis.

Netanyahu warned the Palestinians on Thursday that they would not win their hoped-for state until they recognize Israel as the Jewish homeland, declare an end to their conflict with Israel and agree to security arrangements to protect Israel.

"The resolution in the U.N. today won't change anything on the ground," Netanyahu declared. "It won't advance the establishment of a Palestinian state, but rather, put it further off."

The Palestinians have resisted demands to recognize Israel as the Jewish homeland, saying it would undermine the claims of Palestinian refugees and their millions of descendants scattered across the world.

Israel says Palestinian the demand for refugees to return to what is now Israel is an illegitimate attempt to undermine the Jewish character of their state. Instead, Israel says refugees should be resettled in a future Palestine alongside Israel.

General Assembly recognition on Thursday of Palestine will not actually deliver a state, end the Israeli occupation or reunify the Palestinians, who are ruled by dueling governments in the West Bank and Gaza.

But the Palestinians hope U.N. recognition will add weight to their claims.

Israel, like the U.S., argues that the Palestinians can win a state only through negotiations, and both countries mounted an aggressive campaign to try to head off the General Assembly vote.

The U.N. bid is crucial to maintaining Abbas' leadership. The Islamic militant Hamas group's standing in the Arab world has risen as changes sweep the Mideast, while Abbas' Fatah movement, which governs the West Bank, has been sidelined and marginalized, in large part because of his failure to deliver a state through diplomacy. Hamas got a major boost earlier this month, claiming victory after battling Israel in eight days of hostilities that ended with an Egyptian-brokered cease-fire.

The rival Palestinian governments emerged after Hamas seized Gaza from Abbas in 2007, reducing his control to parts of the West Bank.

Hamas supporters took part in Thursday's celebrations. In the West Bank city of Hebron, some in a crowd of several thousand raised green Hamas flags, while in the city of Ramallah, senior figures of Hamas and Islamic Jihad, two militant groups normally opposed to Abbas, addressed the crowd.

"It's the right step in the right direction," Nasser al-Shaer, a former deputy prime minister from Hamas, said of the U.N. bid.

In Hamas-ruled Gaza, several thousand took to the streets, most of them Abbas loyalists. Marchers hoisted Palestinian flags and chanted, "We want our state, today is our date."

In Jerusalem, about 30 Israeli activists opposing the bid tried to burn a Palestinian flag near a U.N. building in Jerusalem, Israeli police spokesman Micky Rosenfeld said. One person was arrested.

Israel has tempered its threats of retaliation, appearing to back off from plans to immediately punish the Palestinians for the initiative.

Months ago it suggested new settlement construction would be Israel's response to the Palestinians' statehood bid. Now officials are saying they will wait to see whether the Palestinians use their new standing to pursue war crimes charges against Israel in the International Criminal Court, a U.N. body. If so, they threaten punitive measures but have not given details.

Backing for the Palestinians' appeal to the U.N. came from an unexpected quarter Thursday, when former Israeli Prime Minister Ehud Olmert was quoted as saying the Palestinian request "is congruent with the basic concept" of the two-state solution.

"Therefore, I see no reason to oppose it," said Olmert, according to The Daily Beast news website. An Olmert spokesman did not return a call for comment.

Olmert, Abbas and their teams conducted peace talks in 2007 through early 2009, but never clinched a deal.