WASHINGTON — The United States and Iran have agreed in principle for the first time to one-on-one negotiations over Iran’s nuclear program, according to Obama administration officials, setting the stage for what could be a last-ditch diplomatic effort to avert a military strike on Iran.
Iranian officials have insisted that the talks wait until after the presidential election, a senior administration official said, telling their US counterparts that they want to know with whom they would be negotiating with.
News of the agreement — a result of intense, secret exchanges between US and Iranian officials that date almost to the beginning of President Barack Obama’s term — comes at a critical moment in the presidential contest, just two weeks before Election Day and the weekend before the final debate, which is to focus on national security and foreign policy.
It has the potential to help Obama make the case that he is nearing a diplomatic breakthrough in the decade-long effort by the world’s major powers to curb Tehran’s nuclear ambitions, but it could also pose a risk if Iran is seen as using the prospect of the direct talks to buy more time.
It is also far from clear that Obama’s opponent, Mitt Romney, would go through with the negotiation should he win election. Romney has repeatedly criticized the president as showing weakness on Iran and failing to stand firmly with Israel against the Iranian nuclear threat.
The White House denied that a final agreement had been reached.
‘‘It’s not true that the United States and Iran have agreed to one-on-one talks or any meeting after the American elections,’’ Tommy Vietor, a White House spokesman, said Saturday evening. He added, however, that the administration was open to such talks, and has ‘‘said from the outset that we would be prepared to meet bilaterally."
Reports of the agreement have circulated among a small group of diplomats involved with Iran.
There is still a chance the initiative could fall through, even if Obama is re-elected. Iran has a long history of using the promise of diplomacy to ease international pressure on it. In this case, US officials said they were uncertain whether Iran’s opaque supreme leader, Ayatollah Ali Khamenei, had signed off on the effort. The US understandings have been reached with senior Iranian officials who report to him, an administration official said.
Even if the two sides sit down, US officials worry that Iran could prolong the negotiations to try to forestall military action and enable it to complete critical elements of its nuclear program, particularly at underground sites. Some US officials would like to limit the talks to Iran’s nuclear program, one official said, while Iran has indicated that it wants to broaden the agenda to include Syria, Bahrain and other issues that have bedeviled relations between Iran and the United States since the American hostage crisis in 1979.
‘‘We've always seen the nuclear issue as independent,’’ the administration official said, speaking on the condition of anonymity because of the delicacy of the matter. ‘‘We’re not going to allow them to draw a linkage.’’
The question of how best to deal with Iran has political ramifications for Romney as well. While he has accused Obama of weakness, he has given few specifics about what he would do differently.
Moreover, the prospect of one-on-one negotiations could put Romney in an awkward spot, since he has opposed allowing Iran to enrich uranium to any level — a concession that experts say will probably figure in any deal on the nuclear program.
