Kennedy’s historic call for diplomacy was not lost on President Barack Obama on Wednesday.

　　“He [Kennedy] rejected the prevailing attitude among some foreign policy circles that equated security with a perpetual war footing. Instead, he promised strong, principled American leadership on behalf of what he called a practical and attainable peace,” Obama said at American University in Washington.

　　Obama to Iran Deal Critics: Choose Diplomacy Over War

　　Calling the Iran nuclear agreement the “most consequential debate” the United States has had since the 2002 decision to invade Iraq, Obama warned U.S. lawmakers against blocking what he called a “very good deal.”

　　“We have to be honest. Congressional rejection of this deal leaves any U.S. administration that is absolutely committed to preventing Iran from getting a nuclear weapon with one option: another war in the Middle East,” Obama said.

　　Diplomacy or war

　　In a nearly hourlong speech, Obama laid out a forceful rebuttal to critics of the nuclear agreement reached in July between Iran and the P5+1 nations —  the United States, Britain, France, Russia, China and Germany. He said U.S. lawmakers had a stark choice “ultimately between diplomacy or some sort of war.” The latter, he said, would be far less effective in preventing Iran from getting a nuclear weapon.

　　“It would likely guarantee that inspectors are kicked out of Iran. It is probable that it would drive Iran’s program deeper underground. It would certainly destroy the international unity that we spent so many years building,” the president told an audience that included ambassadors from P5+1 nations.

　　He noted that the same people who are against the Iran deal supported the Iraq war, a conflict in which thousands of lives were lost and nearly $1 trillion spent.

　　Rallying Congress

　　U.S. lawmakers have until September 17 to approve or vote down the deal. The president can veto any disapproval, but he needs the support of his fellow Democrats to ensure his veto is not overridden and the deal goes forward.

　　Hours before the speech, Senate Republican Majority Leader Mitch McConnell called for a serious debate on the agreement in September, noting “widespread, well-founded and bipartisan” concerns.

　　“It’s clear that this deal is making members of both parties uneasy, and with good reason. America’s role in the world, its commitment to global allies, and the kind of future we will leave our children are all tied up in this issue,” the Kentucky Republican said.

　　Speaking on the Senate floor, McConnell cited concerns expressed by Democratic lawmakers that the agreement lacks sufficient safeguards, could lead to nuclear weapons race in the region and leaves limited options to prevent Iran’s nuclear breakout.

　　Rebutting critics

　　Obama addressed many of those concerns, including the assertion that the agreement is not strong enough.

　　“The prohibition on Iran having a nuclear weapon is permanent.  The ban on weapons-related research is permanent. Inspections are permanent,” he said. “It is true that some of the limitations regarding Iran’s peaceful program last only 15 years.  But that’s how arms control agreements work.”

　　He also pushed back at those who say sanctions relief will embolden Iran. He spoke at length about Prime Minister Benjamin Netanyahu’s opposition to the deal, contending that the Israeli leader was wrong.

　　“To friends of Israel, and to the Israeli people, I say this: A nuclear-armed Iran is far more dangerous to Israel, to America and to the world than an Iran that benefits from sanctions relief,”  he said.

　　The president said those who believe the U.S. can walk away from the deal and still maintain pressure on Iran through continued sanctions were “selling a fantasy.”

　　Obama ended his speech by noting that lawmakers’ rejection of a diplomatic solution would perhaps do most damage to the image of the United States in the eyes of the world.

　　“If Congress kills this deal, we will lose more than just constraints on Iran's nuclear deal or the sanctions we have painstakingly built," he said. "We will have lost something more precious: America's credibility as a leader of diplomacy.”