"The only peace that will endure is one based on reality, on unshakable facts," Netanyahu said, leaning intently toward a grim Obama in the news appearance that followed an unexpectedly long, three-hour meeting.
Obama acknowledged the chasm. "Obviously there are some differences between us in the precise formulation and language, and that's going to happen between friends," he said.
The clash was remarkable even by the standards of frequently fractious ties between U.S. and Israeli leaders. Obama and Netanyahu sat, mostly stiff and unsmiling. It has contributed to worry among Israelis, who prefer that their leaders be on good terms with the Americans.
Netanyahu was furious the day before about the nature of Obama's plan and felt he had received little notice of it. He declared going into Friday's meeting that he hoped Obama would ease his position on the question of boundaries and other elements of the plan.
But Obama gave no indication of yielding ground. By the time the two spoke publicly Friday, White House officials were prepared for Netanyahu's reaction and said they were not angered by the Israeli's aggressive approach.
Aides said they felt no compulsion to have Obama provide an immediate retort. One official said Obama's proposal succeeded in placing the U.S. position on the record and may one day prove an important part of the international dialogue.
Obama is under growing pressure from Arab states and European governments to lay out a plan to revitalize the moribund talks, and has wanted to show ordinary Arabs that the United States remains committed to peace, especially in the midst of democratic uprisings in the region.
Tactically, administration officials feared the spread of perceptions that talks have failed, which could fuel Palestinian efforts to win U.N. recognition as a sovereign state, embarrassing the United States and creating thornier international problems.
The proposal to base talks on 1967 lines, with "mutually agreed" land swaps, as Obama put it, has been among informal parameters for peace talks that administration officials have long considered - and is similar to proposals by previous presidents. But Obama until now had not offered his own parameters, preferring to leave that to talks between the Palestinians and the Israelis.
A White House official said Friday that laying out recommendations now "provides a new basis for future negotiations to succeed."
Israelis are divided on the issue of the 1967 lines as the basis for talks. Some accept the concept of using 1967 lines, with agreed-upon land swaps, as a starting point. Former Prime Ministers Ehud Olmert, Ariel Sharon, and Ehud Barak have negotiated on groundwork that included those lines.
Opposition leader Tzipi Livni, from the centrist Kadima Party, accused Netanyahu of overreacting and endangering Israel's relationship with the United States for "no essential or critical reason."
By launching the U.S. proposal, however, Obama risked further damaging relations with Netanyahu that have been tense for most of the last 21/2 years.
The days ahead bring opportunities to revisit the argument, as Obama addresses a large U.S. pro-Israel group Sunday and Netanyahu addresses a joint session of Congress on Monday.
Republican politicians have criticized the president, but there is little indication Obama sees the tension as a major political liability among Israelis, foreign countries, or U.S. voters. However, Republicans in Congress tend to rally around Netanyahu, giving the Israeli leader another potential political lever.
Spelling out his arguments in the Oval Office session Friday, Netanyahu said that Israel could never return to the 1967 boundaries because they made Israel so geographically narrow that it would be "indefensible" under an attack.
Likewise, he argued that Israel would be at risk if it withdrew its troops from the Jordan Valley. Obama's plan calls for Israel to make a phased but complete withdrawal from the West Bank.
Netanyahu also took a harsher view of Hamas, the extremist Palestinian faction that is joining the Palestinian government, than did Obama.
While Netanyahu described it as a "terrorist organization," Obama called it "an organization that has resorted to terror."
Administration officials noted, however, that Netanyahu could have used the opportunity to offer an even longer list of grievances, as he had done a day earlier in Jerusalem, but that he refrained, a sign that tensions may ease.
Obama received words of assurance about his course of action from at least one ally.
"I think the proposal to take the 1967 borders and to consider the exchange of territory would be a good and practicable path," German Chancellor Angela Merkel said Friday in Berlin.