As Iran starts its renewed push to peacefully defuse international tensions surrounding its nuclear program, hardliners in both Tehran and Washington are threatening to pounce on failures in the negotiations to wring major concessions from their foreign counterparts, issue experts said.
Iran's political establishment could rein in its new, relatively moderate leaders if negotiations launched on Tuesday with six other nations promise no fast relief from global sanctions. Hawkish U.S. lawmakers, though, are pressing for new economic steps to punish Tehran.
The closely watched two-day meeting in Geneva brings Iran together with the United States and five other countries seeking to clear up fears that the Middle Eastern nation is pursuing a nuclear-arms capability under the guise of a peaceful nuclear program. Attendees include Iranian Foreign Minister Mohammad Javad Zarif, U.S. Under Secretary of State Wendy Sherman, and Catherine Ashton, the European Union's top diplomat and chief interlocutor for the six powers negotiating with Tehran.
At a Monday panel discussion in Washington, a former Obama administration official said Tehran's conservatives "will use any failure in diplomacy to bludgeon" Zarif and Iranian President Hassan Rouhani.
Meanwhile, "hawks" in Washington appear ready to "go all in on sanctions with the approach of regime change," said Colin Kahl, who was assistant secretary of Defense for the Middle East from 2009 to 2011.
A veteran U.N. negotiator, speaking with Kahl at the National Iranian American Council's Third Annual Leadership Conference, voiced doubt that Washington's "major centers of power have reached a conclusion that a deal must be struck" with the government in Tehran.
Proponents of further sanctions in Congress are "going to complicate the negotiation process significantly," said Giandomenico Picco, a former assistant U.N. secretary general for political affairs.
He added: "Those in the leadership of Iran who are suspicious of American intentions are going to become even more suspicious."
The potential for Iran to enrich uranium into nuclear-bomb fuel makes its growing capacity to refine the material a key concern for the five permanent U.N. Security Council member nations and Germany.
Tehran insists the effort would strictly generate material for energy production and other nonmilitary atomic activities.
Steps by U.S. lawmakers in the House of Representatives to further tighten Iran's economic isolation, by broadening sanctions against the country, could leave Rouhani with little room to negotiate a compromise, according to participants on the panel at the Washington conference.
Iranian negotiators are seeking curbs on sanctions steadily piled on the country by the United Nations, the European Union, the United States and other nations.
However, U.S. Senate Foreign Relations Committee Chairman Robert Menendez (D-N.J.) and nine colleagues offered no potential relief from existing penalties in a Friday letter to President Obama.
Instead, they offered only to suspend "the implementation of the next round of sanctions currently under consideration by the Congress." The House of Representatives in July passed a bill designed to cut off nearly all of Iran's remaining international oil sales. The Senate, though, has not yet considered the legislation.
Menendez and the other senators wrote that in return for a "suspension" in implementing potential new sanctions that Congress is weighing, they want Tehran to fully suspend uranium enrichment, among other steps.
"The intent of sanctions is to force Iran to halt and dismantle its nuclear weapons program," their letter to Obama states. "Once this goal has been accomplished in a real, transparent, and verifiable way we will be prepared to remove existing sanctions in a measured, sequenced manner."
Rouhani has declared any permanent uranium-enrichment halt to be off the table. Iranian negotiators reportedly want a "road map" from this week's meeting to establish Tehran's right to a domestic uranium enrichment program as a longer-term objective of discussions.
At the Washington conference, the one-time Obama administration official voiced doubt that Tehran would agree to fully cease its uranium enrichment.
"A deal that zeroed out Iranian enrichment … would be better from a nonproliferation perspective [but] I just don't think that this Iranian regime can agree to such an arrangement," Kahl said.
The former Pentagon official advocated a "good-if-imperfect deal" that would reduce Iran's enrichment capacity and uranium stockpile, bolster international audits of its nuclear sites and bar the nation from enriching uranium beyond a low purity suited only for use in power plants. He added it would be crucial to address Iran's preparation of a heavy-water reactor that could give the nation a route to a plutonium-based bomb.
"In the initial stages of a deal, you wouldn't require congressional action," Kahl said, noting that Obama could act alone in lifting executive-branch penalties.
"The real challenge is if a series of confidence-building interim steps is actually successfully implemented, then the administration would have to make the case to Congress for more enduring sanctions relief, and that will be a very tough sell," he said.
Iran is on track by the middle of next year to become capable of generating enough highly enriched uranium for a single bomb fast enough to evade detection by international monitors, according to a July analysis by the Institute for Science and International Security in Washington.
"At that so-called 'breakout point,' I think decisions related to when diplomacy comes to an end may have to be reached," Kahl said.
Friday's letter was signed by Menendez as well as senators Kelly Ayotte (R-N.H.), Roy Blunt (R-Mo.), Robert Casey (D-Pa.), Christopher Coons (D-Del.) Lindsey Graham (R-S.C.), John McCain (R-Ariz.), Barbara Mikulski (D-Md.), Patty Murray (D-Wash.) and Charles Schumer (D-N.Y.).