(CNN) — The fate of the Iran deal hangs smack in the middle of the 2016 presidential race.

The agreement — set to last for 10 to 15 years — places restrictions on Iran’s nuclear program and reduces its nuclear capacity in exchange for lifting sanctions in phases once Iran holds up its end of the agreement. The White House was able to get the deal through despite strenuous opposition from Republicans on Capitol Hill and the campaign trail, and polls showing the majority of Americans are opposed to it — and it will see that it’s implemented as long as Barack Obama is president.

In addition, the international community is almost universally united behind it. World leaders are gathering in New York this week for the United Nations General Assembly and are sure to largely endorse the agreement. With the exception of Israeli Prime Minister Benjamin Netanyahu, nearly every leader attending has come out in favor of it.

So, how will the next commander in chief treat the deal? Will he or she keep it or get rid of it? And how will a future president’s policy be affected by the world’s opinions?

Not surprisingly, the views among the 2016 presidential candidates are as varied as the field itself.

In an effort to distinguish themselves on the campaign trail, many of the Republican candidates have sought to outdo each other with tough rhetoric. New Jersey Gov. Chris Christie said recently that Obama has “shoved down the throats of the American people the worst foreign-policy mistake.” Former Arkansas Gov. Mike Huckabee evoked the Holocaust by saying the deal is “akin to marching Israelis to the oven.”

Sens. Ted Cruz of Texas and Marco Rubio of Florida, meanwhile, have pledged to tear up the agreement upon taking office. Rubio has said he would “simply reimpose the sanctions” that would be lifted as part of the deal. Real estate mogul Donald Trump, former Hewlett-Packard CEO Carly Fiorina and Sen. Lindsey Graham of South Carolina have suggested they would seek to negotiate a new deal with tougher terms for Iran.

But despite Rubio’s assertion, none of that will be “simple.”

With five other world powers party to the negotiations and pact, and with the U.N. Security Council having endorsed it this summer, it is now enshrined in international law and will be difficult to roll back. Even if the U.S. reneges on its commitments, other countries lining up to do business with Iran will not do an about-face if Iran plays by the rules.

And a “new deal”? There is no reason to believe Supreme Leader Ayatollah Ali Khamenei, who has the final say on Iran’s foreign policy, would go back to the table for further negotiations. Secretary of State John Kerry, who negotiated the deal, called the idea a “unicorn fantasy.”

Which is part of why pledges to abandon the deal or try to renegotiate a new one have drawn strong disagreement not just from Democrats, but from Republican rivals Jeb Bush, John Kasich and Rand Paul. Paul, a Kentucky senator, and Kasich, the governor of Ohio, pledged to reimpose sanctions only if Iran cheats, which is actually similar to the “snapback” provision included in the deal in the event Iran violates it. Similarly, Bush, the former governor Florida, favors increasing military aid to Israel, which Obama has already promised to do.

Kerry will convene a meeting Monday with ministers from U.K., France, Germany, Saudi Arabia, Turkey and Jordan to discuss Syria. No Russian ministers are expected to be there, according to a State Department official.

Leading Democratic contenders Hillary Clinton, who was involved with earlier stages of the Iran negotiations as former secretary of state, and Vermont Sen. Bernie Sanders have come out in favor of the deal, with Clinton proposing a broader strategy to strengthen its enforcement, confront Iran’s destabilizing activity in the region and strengthen the security of Israel and U.S. Gulf allies in the region.

Although Iranian President Hassan Rouhani has suggested the historic deal could lead to improved U.S.-Iranian relations, neither Clinton nor Sanders has spoken of the deal as an opportunity for a larger diplomatic opening with Iran.

Despite the current bluster, the U.S. response in the end will largely be determined by what Iran does. If Tehran keeps its commitments, it will be hard — if not impossible — to stop the world from moving forward. If Iran cheats and seeks to develop a nuclear weapon, the next commander in chief will be under intense pressure — at home and in Israel — to stop it by any means necessary, including the possible use of military force. The president’s actions leading up to any such decision will affect the level of support for action he or she has from the international community.

Either way, if history is any indicator, campaign rhetoric is unlikely to match what the next president does in office: the victor tends to find that the world becomes far more complex when sitting in the Oval Office than observing it from the trail.

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