The United States and Iran have agreed, for the first time, to hold one-on-one negotiations over Iran’s nuclear program, according to Obama administration officials who spoke to The New York Times on Saturday.

One senior administration official told the newspaper that the Iranians have insisted that the talks wait until after the presidential election, telling their American counterparts that they want to know with whom they would be negotiating.

News of the agreement, which comes as a result of intense, secret exchanges between American and Iranian officials that date almost to the beginning of President 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.

Reports of the agreement have circulated among a small group of diplomats involved with Iran, The New York Times reported.

There is still a chance the initiative could fall through, even if Obama is re-elected, the report said. American officials said they were uncertain whether Iran’s supreme leader, Ayatollah Ali Khamenei, had signed off on the effort. The American understandings have been reached with senior Iranian officials who report to him, an administration official said.

Even if the two sides sit down, American 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 American officials would like to limit the talks to Iran’s nuclear program, one official told the newspaper, 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. “We’re not going to allow them to draw a linkage.”

The administration, officials told The New York Times, has begun an internal review at the State Department, the White House and the Pentagon to determine what the United States’ negotiating stance should be, and what it would put in any offer. One option under consideration is “more for more” — more restrictions on Iran’s enrichment activities in return for more easing of sanctions.

When asked for a response to the report on Saturday, Israel’s ambassador to the United States, Michael B. Oren, told The New York Times the administration had not informed Israel, and that the Israeli government feared Iran would use new talks to “advance their nuclear weapons program.”

“We do not think Iran should be rewarded with direct talks,” Oren said, “rather that sanctions and all other possible pressures on Iran must be increased.”

Within the administration, there is debate over just how much uranium the United States would allow Iran to enrich inside the country, indicated the newspaper. Among those involved in the deliberations, an official said, are Secretary of State Hillary Clinton, two of her deputies — William J. Burns and Wendy Sherman — and key White House officials, including the national security adviser, Thomas E. Donilon, and two of his lieutenants, Denis R. McDonough and Gary Samore.

For years, Iran has rejected one-on-one talks with the United States, but economic pressure may be forcing their hand, the officials said. In June, when the major powers met in Moscow, American officials say that Iran was desperate to stave off a crippling European oil embargo. After that failed, these officials now say, Iranian officials delivered a message that Tehran would be willing to hold direct talks.

A senior American official told The New York Times that the prospect of direct talks is why there has not been another meeting of the major-powers group on Iran.

In the meantime, pain from the sanctions has deepened. Iran’s currency, the rial, plummeted 40 percent in early October.

Even with possible negotiations in the offing, there is no evidence Iran has slowed its fuel production. It continues to make nuclear fuel and has refused to allow international inspectors into key sites. Any negotiation with Iran, American officials said, would have to include highly intrusive inspection regimes.

The White House rejected on Saturday the report of direct talks with Iran, Fox News reported.

According to a statement by National Security Council Spokesman Tommy Vietor, “It’s not true that the United States and Iran have agreed to one-on-one talks or any meeting after the American elections. It has always been our goal for sanctions to pressure Iran to come in line with its obligations.”

This past week, diplomats said Iran has added more uranium enrichment centrifuges at its underground Fordow nuclear plant.

The facility is buried deep underground in order to minimize the risk of an attack on its operations.

A Western diplomat registered with the United Nations’ International Atomic Energy Agency (IAEA) said this week it is believed Iran continues to install centrifuges at the plant.

Last month, a top Iranian official admitted that Tehran had on occasion “misled” IAEA inspectors on a number of issues.