With negotiations repeatedly ending in stalemate and Iran’s nuclear development continuing unabated, President Obama’s Iran policy seems increasingly to be at a dead end. Looking back, however, it’s easy to see how Obama ended up on this particular path—and how it all went wrong. The last few years are a sad tale of how political realities in Washington and Tehran derailed an ambitious plan that, at the outset, seemed to offer the best way out of an intractable foreign-policy challenge. As the Iranian presidential elections approach, there has never been a better time for the administration to rethink its strategy on Iran.

Shortly after assuming office, in March 2009, Obama attempted to begin a dialogue with Iran’s Ayatollah Khamenei, but to no avail. Iran’s last controversial election and the protests that followed occupied most of the attention that summer, and the discovery in September 2009 of a secret nuclear facility at Fordow dashed any remaining hopes for a rapprochement. Under immense pressure from both Congress and the Israeli government, the administration decided that it had little choice but to adopt a harder line.

What resulted was the policy that, four years later, has yet to bear fruit: a “two-track” approach of severe economic sanctions and diplomatic negotiations. In keeping with his preference for international engagement and multilateral action, Obama worked hard to convince skittish world leaders to join in on comprehensive sanctions. In theory, tough sanctions would avoid a military confrontation, mollify hawks in Congress, and leave open the option of continued diplomatic efforts. By upping the ante on Iran, increasing pressure now might actually improve the chances for diplomacy to succeed later.

It was a classic example of what Roger Cohen calls “Obama’s instinct for the middle ground.” It seemed like a win-win-win: the antiwar and prowar camps were both appeased for the time being, and from a sweet spot somewhere between the two, Obama would solve the problem the “right” way—by marshalling international support instead of barreling Bush-style into a unilateral war. All the boxes were checked; everyone was happy. What could go wrong?

Initially, the plan seemed to be working: sanctions laid the foundation for diplomacy by signaling a commitment to stop Iran’s nuclear proliferation without military force. Once Russia and China, which tend to be skeptical of Iran sanctions, were on board, it was clear that the international community meant business. But this advantage was soon overshadowed by two factors.

First, the U.S. invested so much getting sanctions in place that it forgot about the rest of the plan. Originally, sanctions were only half the battle; the promise of sanctions relief would galvanize the diplomatic process further down the line. But simply passing the sanctions was a major effort—the administration had to push hard to get international buy-in, while simultaneously convincing Iran hawks that the military option could wait. Sanctions, originally conceived of as a means to an end, became the White House’s singular focus.

It’s the law of conservation of political energy, the more effort was invested in sanctions, the harder it would be to subsequently unravel the sanctions. As a result, pressure—and pressure alone—inadvertently took over U.S. policy. Former State Department official John Limbert recently remarked, “The sanctions took all the air out of the room. It was 95 percent sanctions, and that was on a good day.” The non-profit group The Iran Project, in a recent paper endorsed by experts including former senator Richard Lugar, former national-security adviser Zbigniew Brzezinski, and former Council on Foreign Relations president Leslie Gelb, hit on this problem by advising that “The United States should now dedicate as much energy and creativity to negotiating directly with Iran as it has to assembling a broad international coalition to pressure and isolate Iran.”

The second problem is tougher: sanctions seem to be eroding, rather than elevating, our position with Iran. A series of unintended consequences seem to have pushed the elusive “yes” from Iran even farther out of reach.

Even though the Iranian economy is faltering as intended, the government has been able to step in and manage the downturn so as to shield its hard-line allies and lower-class support base, while offloading the economic pain onto those who are already inclined to oppose the government. Such is the nature of an authoritarian regime. Today, more and more people depend on the government for favors, and the regime is able to portray itself as the people’s champion against draconian Western punishment. Unfortunately, the otherwise pro-Western population increasingly appears to be buying into that harmful narrative.

All of this might be a reasonable price to pay for getting Iran to negotiate—but that doesn’t seem to be happening, either. In theory, Iran wants sanctions relief so badly that it softens its defiant stance. But the West has constructed a “spider web” of complex, interlocking sanctions that are difficult to unravel, both legally and politically. With each new sanction passed, Iran doubles down on its intransigence, knowing that the sanctions relief it wants cannot be conceivably offered. To take just one example, lifting the Iran Sanctions Act requires the president to certify that Iran no longer poses a “significant threat” to the United States and its allies. Given the long history of U.S.-Iran hostility, this is an unlikely scenario. Iran calculates that it will remain under sanctions even if it does make concessions the nuclear front—and so those concessions continue to elude Western negotiators.

In its rush to squeeze Iran’s economy, the West forgot that the real leverage comes not from sanctions themselves, but from the ability to exchange sanctions relief for concessions—an ability that we no longer seem to have.

Now the United States finds itself in a bind. Within the Iranian government, our interlocutors are unfazed by the economic turmoil. Outside the government, potential Iranian friends are angry with the United States. And at home, none of the factions Obama sought to please are happy. It’s no wonder John McCain recently allowed himself a rare moment of sympathy for Obama, saying “it's very rarely that I'm glad that I'm not the president of the United States, but this is one of [those times].”

So what now?

A plan that made perfect sense four years ago is now being derailed by political pressures, unintended consequences, and the inherent limitations of sanctions as a tool of foreign policy. At this point, ironically, Obama may have to do exactly what he’s been seeking to avoid: put his credibility on the line and risk making some people angry.

A recent report on Iran sanctions policy by the Center for Arms Control and Non-Proliferation is just one of several new studies calling for the United States to shift gears and breathe some life back into the diplomatic process. The Iran Project even suggests a need for a breakthrough a la the Soviet Union or China—the paramount examples of the benefits of engaging with adversaries. After more than three decades of U.S.-Iran hostility, a Nixon-in-China move would certainly be radical, but it could be just what’s needed to salvage an embattled policy. It’s worth noting that second-term presidents tend to look across the oceans to determine their legacy.

Will the normally cautious Obama make a big diplomatic gambit? If he chose to do so, a game-changer could come in the form of a major push for bilateral talks with Iran, a significant new concession on the negotiating table, or some other grand diplomatic gesture. Whatever it is, the maneuver will have to deemphasize sanctions in favor of concession-driven sanctions relief, in order to bring back the diplomatic leverage that is rapidly slipping away.

To be sure, engagement and trust-building won’t be easy. But no one, least of all Obama, ever thought it would be. Though the administration may have forgotten, the Iran policy conceived four years ago was always going to require politically risky moves. Since then, sanctions have offered a convenient way to avoid those risks. But a sanctions-centric policy can only work for so long. Now, a bold move is needed, one that may make Obama some enemies, but may be the only way for the United States to regain the upper hand and finally end a decades-long standoff.

Usha Sahay is the Herbert Scoville, Jr. Peace Fellow at the Center for Arms Control and Non-Proliferation. Laicie Heeley is director of Middle East and Defense Policy at the Center for Arms Control and Non-Proliferation.