In this photo released by the official website of the office of the Iranian Presidency, Iran's President Hassan Rouhani delivers his speech in a public gathering in the city of Rasht during his tour to the northern province of Gilan, Iran, Wednesday, April 15, 2015. Iranian President Hassan Rouhani on Wednesday dismissed pressure from the U.S. Congress over a preliminary deal on Iran's nuclear program, saying that Tehran is dealing with world powers — not American lawmakers.

What obstacles remain in ironing out a nuclear deal with Iran?

For starters, Iran’s most important voice on foreign policy is Supreme Leader Ayatollah Ali Khamenei and he still forcefully articulates “de…