MONTREUX, Switzerland — U.S. officials sought Wednesday to tamp down expectations of a substantial preliminary nuclear deal with Iran by the March deadline while working to move past the political dust kicked up by Israeli Prime Minister Benjamin Netanyahu's criticism of an emerging agreement's contours.
U.S. Secretary of State John Kerry said Washington was well aware of the potential nuclear danger Iran poses to countries in the region and will endorse only an agreement that seriously and verifiably crimps Tehran's ability to make atomic arms.
"We continue to be focused on reaching a good deal, the right deal, that closes off any paths that Iran could have towards fissile material for a weapon and that protects the world from the enormous threat that we all know a nuclear-armed Iran would pose," Kerry told reporters at the end of meetings with Iranian Foreign Minister Mohammad Javad Zarif.
The Iranian diplomat told NBC News on Wednesday, "We believe that we are very close, very close."
The sides hope to have a progress report by late March allowing them to finesse details into a final pact by June. But a senior U.S. official appeared to walk back from the significance of that first stage, describing it as only "an understanding that's going to have to be filled out with lots of detail" by the June final target date.
The official's comments could be an attempt to stretch the interpretation of what should be achieved by March, allowing further negotiations even if nothing more is achieved than a vague declaration.
They contrast sharply with what the West laid down earlier.
Justifying an extension of the talks on Nov. 24, Foreign Secretary Philip Hammond of Britain — one of the five powers backing the U.S. at the talks — said he expected "an agreement on substance" by March. Western and Iranian negotiators said then they would use the time between March and June only "if necessary ... to finalize any possible remaining technical and drafting work."
The U.S. official, who demanded anonymity in line with State Department rules, said President Barack Obama will make a call on whether to continue into June once he sees the March assessment from U.S. negotiators.
Playing down the prospects of any lasting damage to U.S.-Israeli ties caused by Netanyahu's speech to the joint houses of Congress Tuesday, the U.S. official said senior Israeli officials would be briefed by secure phone by top U.S. negotiators on the latest round.
Still the Netanyahu speech is likely to further embolden critics in U.S. Congress who fear the U.S. may accept terms too lenient on Iran. He told Congress Tuesday that the agreement taking shape is dangerous and would allow Iran the ability to develop nuclear weapons.
Last week, senators introduced legislation to give Congress a say over any deal, and Republicans are trying to get it passed even as the talks continue.
The American public appears divided. A new Associated Press-GfK poll shows more than 6 in 10 Americans initially say that they favor Congress instituting new sanctions against Iran, while only 7 percent say they are opposed. Another quarter of Americans say they are neither in favor nor opposed.
But the new poll also finds that 31 percent of those who initially said they support new sanctions say that Congress should hold off if the administration says it would reduce the likelihood of a future deal. In total, about 4 in 10 Americans think Congress should go forward with sanctions even over the president's protests.
The poll of 1,045 adults was conducted online Jan. 29-Feb. 2, with a margin of error of plus or minus 3.5 percentage points.
Netanyahu offered no alternate negotiating tactic beyond urging the U.S. to walk away from the table, a point Kerry noted Wednesday.
If talks are successful, the deal being negotiated will "achieve the goal of proving that Iran's nuclear program is and will remain peaceful." Kerry said. "No one has presented a more viable lasting alternative for how you actually prevent Iran from getting a nuclear weapon."
The focus of his comments to reporters at the Swiss resort town of Montreux reflected U.S. concerns about the potential damage Netanyahu's speech could have on the negotiations by further empowering powerful Republican opponents in Congress.
Zarif dismissed Netanyahu's claims that Iran is close to developing a nuclear weapon. "Mr. Netanyahu has been proclaiming, predicting that Iran will have a nuclear weapon within two, three, four years since 1992," he told NBC News.
"There may be people who may have been affected by the type of hysteria that is being fanned by people like Mr. Netanyahu, and it is useful for everybody to allow this deal to go through," Zarif said.
Kerry planned to meet with Arab Gulf state allies in Riyadh Thursday before sitting down with the foreign ministers of France, Britain and Germany in Paris on Saturday to share the state of the negotiations.