While in Iran, Slattery told Al-Monitor, he met with several senior Iranian officials, including Iranian Foreign Minister Mohammad Javad Zarif, Deputy Foreign Minister and nuclear negotiator Majid Ravanchi, (who was studying at the University of Kansas when Slattery represented the state in Congress); and Rouhani's chief of staff Mohammad Nahavandian, who Slattery says he has known for ten years through an interfaith dialogue he has been involved with.

Slattery, a former six-term Kansas Democrat, traveled to Iran December 9-10 to address the international "world against violence and extremism" (WAVE) conference, an initiative of Iranian President Hassan Rouhani. The Topeka Capital-Journal first reported on his trip Jan. 2.

“It is going to require some give on both sides, but I think it is reachable,” he said, adding that a nuclear agreement “would be good for Iran, it would be good for the U.S. and … Israel, and it holds the promise of fundamentally realigning the Middle East.”

“I believe we have a historic opportunity,” Slattery, who represented Kansas in the U.S. House of Representatives from 1983 to 1995, told Al-Monitor in an interview Jan. 2. “I believe the leadership in Iran and the U.S....all want to pursue a negotiated resolution of this problem around the nuclear issue, and I believe a deal is reachable.”

Former U.S. Congressman Jim Slattery became one of the only former elected U.S. officials to travel to Iran last month, where he came away from meetings with senior Iranian officials optimistic about prospects for reaching a nuclear deal that would enhance the interests of the United States and its allies, including Israel, he told Al-Monitor.

“They all said, the window of opportunity” for a nuclear deal “is open, but it will not stay open forever,” Slattery told Al-Monitor. Regarding the officials he met with, “I think…really many of them have perhaps bet their political careers on getting agreement on this nuclear issue.”

Slattery, currently a partner at Wiley Rein law firm in Washington DC, said he has been involved in interfaith, “track 2” dialogue for the past decade through a group called the Abrahamic Dialogue, based out of Catholic University. He says that he has become a strong advocate of what fellow former Kansan Dwight Eisenhower called “people to people” diplomacy.

On his trip to Iran last month, he said, that included friendly banter with Iranian passport control officers who, seeing his US passport, expressed interest in meeting American women.

“I was going through the passport control office in Tehran, and these young men checking passports… were anxious to meet American women,” Slattery said. “You know, it’s the same all over the world.”

“When I was in Tehran, walking on the streets, I went to the bazaar, in the lobbies of hotels, I sensed no animosity towards me as a westerner and American,” he recalled. “Several people asked me if I was an American.” He said he felt much safer and more welcome by people in Tehran than when he served as an election monitor in Baghdad over a year ago.

A nuclear deal could help thaw US Iran relations, and eventually make way for efforts to reduce hostilities between Iran and Israel, Slattery said.

“I believe smart Israelis should recognize that a relationship with Iran is vitally important to Israeli security,” Slattery said. “I believe smart diplomats can [eventually] get to a point where we can have a relationship between Iran and Israel that will permit peaceful co-existence.”

“There will be domestic forces in the United States that will not want to see an agreement,” he said. “I think you can hear some messaging has already started that would have us believe Obama is selling out Israel," Slattery said. "I think that is false."

Of the skepticism about an Iran nuclear deal expressed by some of his former colleagues on Capitol Hill, Slattery said he hopes U.S. lawmakers wait to see what is in any agreement reached before dismissing it.

“I hope American politicians will resist the temptation to make short-term [political] hay that could cost the opportunity to complete a very important and constructive agreement with Iran that would be good for Israel, Iran and the United States,” he said.

“I just think we need to pursue all diplomatic options,” he added. “We have made tremendous progress.”