With his endorsement Thursday of a key Palestinian statehood demand, President Obama just rolled the dice with a small but vital segment of his base -- the American Jewish community.

Obama, while picking up the lion's share of the Jewish vote in 2008, has since the beginning of his term faced questions about his commitment to the U.S.-Israel alliance. His administration has sought to quell these concerns by stating in whatever forum possible that their bond is "unshakable" -- a line he used again Thursday.

But the president's call for a Palestinian state based on the borders that existed before the 1967 Six-Day War seemed, to some, to place him on the side of the Palestinians at the starting point of what he hopes will be a new round of peace talks.

The Israelis were not pleased.

"This is a radical shift in U.S. policy toward Israel," Dore Gold, former Israeli ambassador to the United Nations, told Fox News. "Frankly, the 1967 lines are not defensible. ... Israel today is 45 miles wide. You put us back to the '67 lines, we are eight miles wide."

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Israeli Prime Minister Benjamin Netanyahu, who is set to meet with Obama on Friday, had a similar reaction. His office said in a statement that while Israel "appreciates" Obama's commitment to peace, the prime minister essentially wants Obama to retract his remarks.

In the U.S., the policy shift could pose a problem for Obama with Jewish voters and donors.

"I think that if the perception is a year from now that the president's game plan was to sort of ram this approach through, then he's going to lose a lot of this support," said Rabbi Abraham Cooper, associate dean at The Simon Wiesenthal Center, a Jewish rights group in Los Angeles. "It'll be interesting to see how Americans Jews respond."

Jewish voters made up just 2 percent of the electorate in 2008, according to exit polls. But they leaned toward Obama. At the time, 78 percent voted for the senator from Illinois, while just 21 percent voted for Republican Sen. John McCain.

According to information kept by the Center for Responsive Politics, a little more than half of donations from "pro-Israel" political action committees went toward Democrats in 2008 -- the bulk of it, $1.16 million, went to Obama.

Cooper gave the president high marks for his Middle East speech Thursday, outside of the 1967 border component. He said the broader response from American Jews will ultimately depend on the course of events over the next year -- notably, a planned U.N. vote this September for Palestinian statehood. Obama announced opposition to the resolution Thursday, and Cooper suggested American Jews will want to see how firmly the Obama administration fights that initiative.

Malcolm Hoenlein, executive vice chairman of The Conference of Presidents of Major American Jewish Organizations, said it's too early to tell whether the courtship between Obama and American Jews is in peril.

"We should wait and see what he outlines" in the days ahead, Hoenlein said, referring to his upcoming speech at AIPAC. But Hoenlein said he's hearing considerable concern that Obama just made the 1967 borders the "starting point" for negotiations with the Palestinians -- rather than something the two sides might arrive at down the road. He said the Palestinians can now "pocket this" and use it to influence talks.

"It's a sensitive issue," he said.

Perhaps seeing an opening to make Israel a campaign issue, likely 2012 Republican candidates blasted out statements condemning the president's declaration, backed up by Republicans in Congress.

"President Obama has thrown Israel under the bus. He has disrespected Israel and undermined its ability to negotiate peace," former Massachusetts Gov. Mitt Romney said.

"President Obama's insistence on a return to the 1967 borders is a mistaken and very dangerous demand," former Minnesota Gov. Tim Pawlenty said.

Several Jewish groups, anticipating the backlash, sprung to the president's defense after the policy bombshell Thursday at the State Department.

Liberal Jewish group J Street announced that it "wholeheartedly endorses" the president's outline.

"He is correct in saying that Israel will only find security through granting the Palestinian people their freedom, and the Palestinian people will only achieve freedom if Israel finds security," the group said.

The National Jewish Democratic Council offered similar praise, calling his approach "pragmatic" and arguing that his framework is far from radical.

"There will be the naysayers who can find something to protest from this address, including what is widely accepted wisdom -- that a final resolution will ultimately be based on 1967 lines with mutually agreed swaps," the group said. "But the fact is that this speech and the policies it represents are replete with unwavering, unshakable support for Israel."

Obama sought to assure Israel on Thursday that the U.S. remains committed to the country's security.

In his speech, he said Israeli's right to defend itself will remain paramount, and he suggested the recent unity agreement between Fatah and Hamas, which the U.S. deems a terrorist group, is problematic for negotiations.

He also publicly rejected attempts by the Palestinians to gain recognition for their own state before the United Nations. "Symbolic actions to isolate Israel at the United Nations in September won't create an independent state," Obama said.