Two of the top candidates for the Republican nomination for president are fighting over the Iran deal. Governor of Wisconsin Scott Walker says he’d tear up the Joint Comprehensive Plan of Action on Day 1 of a Walker Administration. That’s a rash novice speaking, says Jeb Bush. The former governor of Florida hates the deal, too, but says he’d have to appoint his national security cabinet and confer with allies first.The truth is that wherever the Republican candidates profess to stand, none of them has the slightest practical influence over the Iran deal. The one and only presidential candidate who does is Hillary Clinton, who can crash the deal a year and a half before the 2016 election. Sure, she already came out with a statement tentatively praising the deal, but with a vote in Congress due in the fall, she still has time to shape the results. If Clinton comes out against the deal, she will start a chain reaction in her own party, with Democrats on the Hill abandoning President Barack Obama’s signature foreign policy initiative like a sinking ship and joining Republicans in an overwhelming No.If on the other hand Clinton says nothing, stays loyal to the president she served, and maintains party unity, the deal will almost certainly sail through Congress untouched. If Clinton becomes president, she will then inherit an agreement nearly guaranteeing that a terrorist-supporting, anti-American, anti-Semitic ruling clique in Iran will continue to spread chaos throughout the Middle East and will likely acquire a nuclear bomb on her watch. Whether Clinton decides to speak out or stay quiet is perhaps the most important decision of a Clinton 45 Administration—a decision that will powerfully shape her own foreign policy legacy and determine what sort of world she will hand off to the future.Barring an Israeli strike on Iranian nuclear facilities—and a recent joint war game with Greece shows that the Israeli Air Force is still working out countermeasures for the S-300 air-defense system that Moscow sold Iran—there are no more wild cards left in the great Iran debate. Everyone is locked in, except for Clinton.After several years of secret talks with Iran starting in 2009, and nearly two years of public negotiations, the Obama Administration is all in on a deal that they are promoting as the centerpiece of the president’s foreign policy legacy. They don’t care that the terms of the Joint Comprehensive Plan of Action have no real inspection and verification regime to make sure that Iran is abiding by the deal because, they say, it is the best possible deal that they could get. John Kerry and his staff don’t mind saying that they were lying about making sure that the agreement would ensure anytime/anywhere inspections of Iranian nuclear facilities. The way they see it, any deal is better than no deal. Sure, the president says his name is on the deal, but he understands better than anyone that the attention span of the American public is no longer than a 12-hour Twitter cycle. He’s confident that someone else will be holding the bag if and when Iran gets the bomb.The Iranians are happy, too. Supreme Leader Ali Khamenei will likely get to see Iran test a nuclear device before he passes from this realm into the next. The IRGC will enjoy a huge windfall with the $150 billion signing bonus even as it further consolidates control of the Iranian economy with European and Asian investors now knocking on their door.French Foreign Minister Laurent Fabius put on a good show for a while, protesting the White House’s continuously weakening position, but it was inevitable the Europeans would eventually fold. Earlier in the week, the U.N. Security Council unanimously approved the Iran deal, and soon the Europeans will be making available the industrial goods—precision tools, etc.—Iran needs to build the bomb.Many Arabs aren’t happy about the deal, but what choice do they have? They know they’re not loved on Capitol Hill or by the American public, so they have little room for a public spat with a president they fear still might hurt them, even with only 15 months left in office. The way the Saudis see it, they’re not family like Israel is, so they’ll accommodate the White House and to a certain extent their Iranian rivals as well and wait to see what happens next.The Israelis are unified in their opposition to the agreement. It’s not just Bibi who bellows that an Iranian bomb is an existential threat to the Jewish state—opposition leader Isaac Herzog also believes it’s a dangerous deal and intends to make his feelings known to U.S. congressmen and senators.But both Bibi and Herzog are certainly wasting their breath—everyone on the Hill has been settled for two years now. The Republicans overwhelmingly dislike the deal, with even neo-isolationist Rand Paul coming out strongly against it. Herzog’s counsel won’t have any effect on the Democrats, even if it’s a little more complicated on the other side of the aisle. Sen. Robert Menendez has long been wary of the administration’s Iran nuclear talks and along with other senators, like Maryland’s Ben Cardin, is displeased the White House wants to circumvent the Hill by getting the JCPOA approved at the U.N. first.Still, it’s not easy to go against the head of your own party, who is enjoying a surge of popularity right now—especially when he threatens to run primary candidates against you as Obama is rumored to have threatened potential Democratic deal opponents. Some observers think this is Chuck Schumer’s big moment, but the reality is that if Schumer were going to go against the Iran deal, he’d have joined forces with Menendez long ago. Schumer apparently detests Netanyahu, and more to the point, he knows there’s a heavy price to be paid within his own party for opposing the president and no price to be paid for going against Israel.This of course is one of the great innovations of the Obama White House. They discovered that you can stick it to Israel and trot out anti-Semitic conceits to scare off potential critics in the pro-Israel community—people shouldn’t read the deal influenced by “lobbying,” Obama said last week, but should rather be guided by U.S. national interests—and the Jews will still vote overwhelmingly Democratic no matter what.Clinton’s decision, meanwhile, isn’t really about Israel or the American Jewish community either. It’s about what kind of party—and what kind of country—she wants to lead.If Clinton were to come out against the Iran deal, she’d give cover to all the Democrats on the Hill who don’t like the deal and don’t trust Obama—and who don’t want to have to explain to their constituents why they voted for an Iranian nuclear mushroom cloud in the desert, or somewhere worse. The Democratic Party would be able to escape being portrayed as the party that gave in to Iranian demands because it was so bedazzled by the promise of a second Nobel Peace Prize and the illusory hope of peace at any price. Consequently, the JCPOA would be resoundingly defeated, letting the Democrats slip the noose of Obama’s foreign policy failures, and stripping the Iranian nuclear weapons program of the international legitimacy granted by the deal.It’s a no-brainer for Clinton, unless she wants to be the last one standing in a game of musical chairs and inherit an international order more dangerous than at any time since the Cold War. It’s true that the Iranian military is a far cry from a Red Army capable of overrunning Europe, but that’s precisely why Tehran seeks the bomb. A nuclear weapon fixed on ballistic missiles, including missiles that will soon be able to reach the United States, makes a regional power like Iran a global threat.The problem for Clinton in opposing the deal may be something closer to home—the threat that Obama will support a primary challenger to her and release those 30,000 emails from her private server that the White House has in its possession and is now presumably investigating. If she comes out against the Iran deal, the administration will leak something—or many things—capable of doing irreparable harm to her candidacy.If Clinton comes out against the Iran deal, she might not get to be president. If she gives the deal her blessing, she’ll be wrestling for eight years with a tiger that her predecessor left on her doorstep and she brought in the door. Either way, Obama has booby-trapped Clinton’s White House.***Like this article? Sign up for our Daily Digest to get Tablet Magazine’s new content in your inbox each morning.