U.S. President Barack Obama has said Iran should agree to at least a decade-long freeze on its nuclear activity for a landmark deal to be reached.
Obama defended a possible agreement with Iran in an interview with Reuters at the White House on March 2, a day ahead of Israeli Prime Minister Benjamin Netanyahu's planned speech to U.S. Congress opposing a deal.
"If, in fact, Iran is willing to agree to double-digit years of keeping their program where it is right now and, in fact, rolling back elements of it that currently exist...if we've got that, and we've got a way of verifying that, there's no other steps we can take that would give us such assurance that they don't have a nuclear weapon," Obama said.
The U.S. goal is to make sure "there's at least a year between us seeing them try to get a nuclear weapon and them actually being able to obtain one," Obama added.
He also said the odds were still against sealing a final agreement with Tehran.
Obama suggested there had been little change in his assessment that the negotiations have less than a 50 percent chance of success.
The United States, along with Britain, China, France, Germany, and Russia, are seeking a deal with Iran under which Tehran would limit its nuclear program in exchange for sanctions relief.
The six powers and Iran have set an end-of-March deadline for a framework agreement and a June 30 deadline for a full deal.
Israeli officials say any agreement that leaves Iran with a workable nuclear industry is too dangerous.
Speaking on the eve of his polarizing speech to Congress, Netanyahu said a nuclear deal with Iran "could threaten the survival of Israel."
He told the American Israel Public Affairs Committee conference in Washington, "I have a moral obligation to speak up in the face of these dangers while there is still time to avert them."
At the conference, U.S. national security adviser Susan Rice said Washington was seeking a deal that would cut off "every single pathway" Iran has to producing a nuclear weapon.
She also warned against holding out for "unachievable" outcomes, such as getting Iran to fully end domestic enrichment.
Obama downplayed Israeli concerns, telling Reuters the Israeli prime minister had been wrong on Iran before, when he opposed an interim agreement last year.
"Netanyahu made all sorts of claims -- this was going to be a terrible deal, this was going to result in Iran getting $50 billion worth of relief, Iran would not abide by the agreement," Obama said.
He said that none of that has come true.
"We've seen Iran not advance its program," Obama said. "In many ways, it's rolled back elements of its program."
But both Obama and Netanyahu moved to dial back tensions.
Netanyahu said the relationship between his country and the United States was "stronger than ever" and not in crisis, and insisted that he was not in Washington to "disrespect" the president.
Obama -- who has refused to meet with Netanyahu during his visit -- said such differences of views would not be "permanently destructive" to U.S.-Israeli ties.
Obama also criticized plans by U.S. lawmakers to impose additional sanctions on Iran if no deal is reached by June 30.
"I'm less concerned, frankly, with Prime Minster Netanyahu's commentary than I am with Congress taking actions that might undermine the talks before they're completed," he said.
Netanyahu's speech comes with U.S. Secretary of State John Kerry holding a second day of talks on Iran's nuclear program with Iranian Foreign Minister Mohammad Javad Zarif in Montreux, Switzerland.
Kerry said on March 2 that there had been some progress but there was "a long way to go and the clock is ticking."
Zarif said a deal could be concluded this week if the negotiating sides have sufficient political will and agree to remove sanctions on Tehran.
"If they want an agreement, sanctions must go," he said.