Moreover, Mr. Ross said, Iran’s recent statements signal that its leaders are preparing their domestic audience for concessions. Iranian officials have declared that the West has effectively endorsed Iran’s right to enrich uranium, a step they portrayed as a major strategic coup. American officials insist the United States has not done that and has been deliberately ambiguous about whether it would ever grant Iran the right to enrichment.

Still, as Mr. Ross said, “if you’re looking for a way to present a compromise, you want to present it as a victory.”

Like other experts, he added a cautionary note. After an initial meeting in Istanbul last month that served mainly to test if Iran was willing to talk seriously about its nuclear program, the United States and its partners must now get into the kinds of nitty-gritty issues that torpedoed previous negotiations with Iran.

The major powers’ initial goal is to halt the activity that most alarms Israel: the spinning of thousands of centrifuges to enrich uranium to 20 percent purity, which is within striking distance of the level needed to fuel a nuclear weapon. That would buy time for negotiations over the ultimate fate of a program that Iran claims is for peaceful energy purposes, but that the United States and Israel fear is in pursuit of at least a nuclear weapons capability.

In addition to halting enrichment, officials said, Iran must agree to ship out its stockpiles of 20 percent uranium and to cease operations at an enrichment facility buried in a mountainside near the holy city of Qum, which Israel says could soon be impregnable to an airstrike.

If Iran agrees to those interim steps, officials said, the talks could shift from high-profile meetings once a month to more regular meetings, at working levels, where officials could delve into technical details, like how to ship out the uranium or monitor Iran’s suspension of operations at the plant near Qum, known as Fordo. European Union and Iranian officials have already met in Geneva to prepare the agenda for the meeting in Baghdad.

“You could really use the summer to have weekly, if not daily, meetings to get to the point where the U.S. could say, ‘We think there is a deal out there to avoid war,’ ” said R. Nicholas Burns, who led talks with Iran under President George W. Bush and is now a professor at Harvard. But, he added, the Obama administration “has also got to be willing to walk away from it.”