WASHINGTON — President Obama said Saturday that he believed the chances for a comprehensive nuclear agreement with Iran are 50-50 or worse, yet defended diplomacy as the best way to prevent Tehran from acquiring atomic weapons.
During a question-and-answer session with a pro-Israel audience, Obama said he wasn’t naive about the odds for a successful final agreement between world powers and Iran next year, building on the recent six-month interim deal.
‘‘If you ask me what is the likelihood that we’re able to arrive at the end state ... I wouldn’t say that it’s more than 50-50,’’ Obama said. ‘‘But we have to try.’’
His comments came as Iran’s president urged support for the deal, which eases some of the international community’s crippling economic sanctions in return for a freeze on part of the Islamic Republic’s uranium enrichment activities. He said Saturday that improving the economy is as important as maintaining a peaceful nuclear program.
Since Iran signed the interim agreement last month with world powers, President Hassan Rouhani has been trying to convince skeptics and hard-liners at home that Iran is not compromising on key issues of national sovereignty.
It’s a task that will become all the more difficult for the moderate leader as Tehran moves toward a final accord six months from now.
‘‘Nuclear technology and uranium enrichment is our definite right,’’ Rouhani said in a speech to university students broadcast live on state TV. ‘‘But progress, better living conditions, and welfare for the people is also our definite right. Breaking and dismantling the architecture of the ominous and oppressive sanctions is also our definite right.’’
President Obama’s remark about the likelihood of a final agreement with Iran was somewhat startling. Obama has tried to allay the fears of many Israelis and some Americans that his administration last month promised to ease economic pressure too much in return for too few Iranian concessions.
The comment nevertheless pointed to the difficult talks that await as the United States and its negotiating partners — Britain, China, France, Germany, and Russia — work toward a final pact next year. The goal is to eliminate the possibility of Iran assembling a nuclear arsenal, even if any deal might let Iran continue enriching uranium at lower levels.
Obama said the six-month interim agreement halts and rolls back central elements of Iran’s nuclear program, compelling Tehran to eliminate higher-enriched uranium stockpiles, stop adding new centrifuges, and cease work at a heavy water reactor that potentially could produce plutonium. It also provides time to see if the crisis can be averted through negotiation.
‘‘If at the end of six months it turns out we can’t make a deal,’’ Obama said, ‘‘we are no worse off.’’ Sanctions against Iran will be fully reinstated and even tightened if Iran doesn’t make a final agreement, he pledged.
Obama’s appearance at the Brookings Institution forum appeared directed as much at an Israeli audience as an American one. The discussion was broadcast live on Israeli television, with analysts there viewing it as an effort to patch over Obama’s public differences with Israeli Prime Minister Benjamin Netanyahu.
Netanyahu, who was scheduled to address the same forum Sunday, has called the nuclear agreement in Geneva the ‘‘deal of the century’’ for Iran.
Obama acknowledged some ‘‘significant tactical disagreements’’ with Netanyahu, but said US and Israeli bottom-line goals were the same.
Secretary of State John F. Kerry promised close consultation on next steps with the Jewish state, which includes a visit to Washington this coming week by Yossi Cohen, Netanyahu’s national security adviser.
‘‘We will not allow Iran to acquire a nuclear weapon — period — not now, not ever,’’ Kerry said. ‘‘I am convinced that we have taken a strong first step that has made the world and Israel safer.’’
On Mideast peace hopes, Obama echoed an optimistic assessment provided by Kerry during a trip to Israel and the Palestinian territories this past week.
The president said his administration had spent much time working with Netanyahu to understand Israel’s security needs as part of any two-state solution.
‘‘I think it is possible over the next several months to arrive at a framework that does not address every single detail but gets us to the point where everybody recognizes it’s better to move forward than move backward,’’ Obama said.