One of the major impediments to an agreement next week is Iran’s insistence that the international community formally acknowledge its “right” to continue to enrich uranium. The United States asserts that there is no such right under the Nuclear Nonproliferation Treaty.

But American officials appear to be seeking a solution in which Iran would be allowed to enrich uranium at the low level of 3.5 percent — used to fuel most civilian nuclear reactors — during an interim agreement and under a comprehensive accord. The condition would be that Iran accept a series of limitations, including stringent verification, on its nuclear program to ensure it does not further enrich the uranium to bomb-grade levels and use it to make a nuclear device. Iran now has stockpiles of uranium enriched to nearly 20 percent, which is used to fuel a specialty reactor but is also much closer to weapons-grade uranium.

“I think there is a way to navigate it,” the senior administration official said when asked if a compromise might be found on Iran’s claim of a right to enrich uranium.

The official did not detail the potential compromise. But one solution, Western diplomats say, would be for an interim accord to affirm that Iran would be entitled to all of the rights of signatories to the Nuclear Nonproliferation Treaty. Iran and world powers would then agree to disagree on how to interpret that treaty.

“I am sure that whatever gets agreed to in this document, Iran will argue that they have the right to enrichment,” the senior administration official said, referring to the interim accord now under negotiation. “And we will argue, as I am sure the document will make clear, that nothing has been agreed as to the final dimensions of Iran’s peaceful nuclear program once it can assure the international community that it is peaceful.”