If diplomacy succeeds, he will take credit for it. If diplomacy fails as a result of American sabotage, he will claim vindication. His mistrust of the West will have proven correct, as will his line that Iranís interest is best served by resisting rather than collaborating with the West. Iranís moderates and pragmatists will once again be pushed to the margins of Iranian politics. Rouhani will be weakened and momentum will shift back to Khamenei and the hardliners.
Regionally, Obama will be further weakened, having first seen his attempt to bomb Syria thwarted by the American public and then his diplomacy sabotaged by his own party members in the Senate. Hardliners in Iran see a weakened Obama as beneficial to Iran.
If new sanctions later lead to war with Iran - which Khamenei may believe is inevitable - Iranís Supreme Leader and his regime will be better positioned to survive the confrontation since international support for U.S. military action will be at a minimum.
Ironically, Khamenei finds himself in a surprising position. He doesnít have to do anything. He only needs to patiently wait for Senators Kirk and Menendez to make him a winner by recklessly pushing for sanctions and making America - not Iran - the problem.
If diplomacy is permitted to succeed, however, Khamenei may benefit in the short run, but in the long run, it will present him with one of his greatest challenges thus far: the unleashing of Iranís forces of moderation.
Trita Parsi is president of the National Iranian American Council, and author of ďA Single Roll of the Dice: Obamaís Diplomacy with Iran.Ē
Former Sen. Scott Brown, R-Mass., candidate for U.S. Senate in New Hampshire, holds his hand over his heart during the singing of the national anthem as he waits to take the stage for his town hall campaign rally with Sen. John McCain at the Pinkerton Academy in Derry, N.H., on Monday, Aug. 18, 2014.