JERUSALEM - US-Israel tension over Barack Obama's endorsement of Israel's pre-1967 borders is obscuring a flip side of the Middle East coin: The past days' speeches by the US president contained difficult challenges for the Palestinians as well.

Addressing the American Israel Public Affairs Committee Sunday, Obama reiterated his request that the Palestinians drop their plans to appeal for recognition at the United Nations this fall, and - as he did in another Mideast speech Thursday - raised tough questions about an emerging Palestinian unity government that is to include the Hamas militant group.

Most difficult for Palestinians is Obama's call to recognize Israel as the Jewish homeland, essentially requiring the Palestinians to accept that most refugees will be denied the "right of return" to what is now Israel.

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Perhaps for this reason, the Palestinians have remained largely quiet about the substance of Obama's speeches, seemingly content to watch Israeli Prime Minister Benjamin Netanyahu clash with the US administration over Israel's future borders.

"It's really premature to jump into any of these details," said Saeb Erekat, the chief Palestinian negotiator, when asked by The Associated Press about the demands Obama made of the Palestinians.

The fate of Palestinian refugees is one of the most emotional and explosive issues in the Israeli-Palestinian conflict.

Hundreds of thousands of Palestinians either fled or were expelled during the war surrounding Israel's creation in 1948. Today, the surviving refugees, with their descendants, number several million people.

The Palestinians claim they have the right to return to their family's lost properties. Israel rejects the principle, saying it would mean the end of the country as a Jewish democracy. Israeli leaders say the refugees should be entitled to compensation and resettled in a future Palestine to be established next to Israel, or absorbed where they now live.

In his speech last Thursday, Obama did not explicitly mention the refugees. But by saying a final peace deal must recognize "Israel as a Jewish state and the homeland for the Jewish people," he appeared to back the Israeli position.

The issue is so central to Palestinian policy and society that no Palestinian leader can be seen as abandoning the rights of the refugees, particularly at a time when peace efforts are at a standstill and so many other difficult issues, such as borders and the final status of Jerusalem, remain unresolved.

Nabil Shaath, a senior Palestinian official, said recognition of Israel as a Jewish state would sell out not only the refugees, but potentially open the door to Israel expelling its roughly 1.5 million Arab citizens as well. This idea has never been seriously raised in Israel.

He said the Palestinian recognition of Israel's right to exist, without any reference to national character, should be sufficient.

"We recognize Israel as a state," he said. "It's a recognition of a state to a state."

In his two recent speeches, Obama took aim at two other central planks of Palestinian policy: plans to ask the UN in September to recognize an independent Palestine, with or without a peace agreement; and a unity deal struck between President Mahmoud Abbas' Fatah movement and the Iranian-backed Hamas militants.

In Thursday's speech, Obama warned that "symbolic actions to isolate Israel at the United Nations in September won't create an independent state." And referring to Hamas in Sunday's address to AIPAC, a powerful pro-Israel lobby, Obama stated: "No country can be expected to negotiate with a terrorist organization sworn to its destruction."

"We will hold the Palestinians accountable for their actions and their rhetoric," Obama said.

Erekat insisted the world must embrace the Fatah-Hamas reconciliation, meant to end the split that has left rival governments in the West Bank and Gaza Strip. The Palestinians claim both areas, along with east Jerusalem, for their future state, and Erekat said there can be no independence without reconciliation.

In any case, he said Abbas, and the umbrella Palestine Liberation Organization, dominated by Fatah, are the parties to negotiate peace with Israel - not the "unity government" of the Palestinian Authority which would be backed by both parties.

Erekat, like other Palestinians officials, declined to discuss most of the specifics of Obama's speech, including the issue of the Jewish state. For now, he says the border issue should be the focus of Mideast diplomacy.

The Palestinians demand a return to the pre-1967 lines, which would require an Israeli pullout from the West Bank and east Jerusalem, though they are open to Obama's idea of agreed-upon modifications through land swaps - as long as they are small.

Erekat said if Netanyahu accepts the 1967 lines he could raise any other matter in negotiations. "Before I hear the prime minister of Israel saying that he accepts this principle, I think it would be a waste of my time to discuss any other issue," Erekat said.

Netanyahu says the 1967 lines are "indefensible," and his anger toward the US president seemed palpable at a White House meeting Friday.

But even Obama's reference to the 1967 lines may not be entirely to the Palestinians' liking.

Clarifying his position Sunday, Obama said those lines should be the basis for a peace deal, but that the final borders could be adjusted to accommodate "new demographic realities."

That was seen as a recognition that Israel could keep at least some of the occupied area where it has settled Jews. Some 500,000 Israelis live in Jewish settlements, which are considered illegal by the Palestinians and the international community.

Obama also noted the 1967 lines have long been considered a basis for a final peace deal, most recently in previous negotiations that broke down in 2008. So his embrace of those borders is not revolutionary. "What I did on Thursday was to say publicly what has long been acknowledged privately," he said.

After initial shock and anger toward Obama, members of Netanyahu's hard-line coalition have begun to soften their opposition.

Limor Livnat, a Cabinet minister in Netanyahu's nationalist Likud Party, called Obama's speech on Sunday "excellent." She praised his tough line against Hamas and support for Israel as a Jewish state.

"Following the prime minister's words, the president sharpened his message and said things that he didn't say clearly beforehand," she told Channel 2 TV. "These are important things."