By Jeremy D. Rosner The agreement the Obama administration and key allies negotiated with Iran makes an important contribution toward Mideast stability and American security. It verifiably helps block Iran’s quest for a nuclear weapon and improves the world’s ability to detect and prepare for Iranian violations. It also ends an impressive negotiating saga: The Obama administration built the strongest web of multilateral sanctions ever against Iran, and the economic pain of those sanctions largely forced Tehran to accept limits on its nuclear program.  

The administration’s negotiations with Congress have sadly not been as strong. Under an unwise agreement the administration reached with Capitol Hill this spring, the fate of the Iran accord now rests with Congress, which can vote to endorse or block the accord by mid-September. Agreeing to let Congress vote in this way unfortunately erodes presidential foreign policy prerogatives and subjects the deal to the kind of whip-saw politics that prevail on foreign policy when the U.S. enjoys a period of relative security, or when the U.S. approaches national elections, or worst — like now — both.  

Those dynamics put the Iran agreement in some peril, but Obama can prevail if he manages the Hill battle and the public debate in the right way.  

It may seem odd to call this a period of security given the rise of ISIS, Syria’s civil war, bloodshed in Iraq and Afghanistan, Russia’s invasion of Ukraine, and a host of other crises. Yet for most Americans, and those who represent them in Congress, national security is a bottom-tier concern. In the aftermath of 9/11, Iraq, and Afghanistan, voters in 2012 and 2014 said it was their least pressing issue, according to the exit polls, well behind economic and social concerns.  

When security challenges are less urgent for voters, the political risk of challenging the commander in chief lessens, and members of Congress are more likely to use foreign policy as a political football. That goes double during presidential campaign seasons. The outrageous comments by some GOP presidential contenders, such as Mike Huckabee’s claim that the accord marches Israelis “to the door of the oven,” suggest opposition is as much politics as substance. Just as the Treaty of Versailles died in the Senate just after World War I, and the Senate blocked the Comprehensive Test Ban Treaty just after the Cold War, we are again in just the kind of post-conflict environment where diplomatic agreements can run into serious Hill trouble.  

Fortunately, Obama and his team have a good deal of room to maneuver. History demonstrates that public opinion generally needs to be over 60 percent on a national security issue before it starts to force the direction of policy. Public polls on the Iran accord generally show modest support (Washington Post, 56-37 percent in favor, after reading a description of the accord) or modest opposition (Pew, 33-45 percent against, with no description; CNN, 44-52 percent against, with a short description), but none with strong opposition.  

The Iran deal is a passionate issue for certain slivers of the electorate — especially conservative Republicans, 82 percent of whom oppose the accord, according to Pew. And as the Hill debate advances and the first GOP presidential debate is held, public opinion will almost certainly polarize even more along partisan lines.  

But apart from conservative Republicans, polls suggest most voters approach the issue with a permissive mixture of feelings. They support dealing with Iran diplomatically, yet doubt Iran will comply with the deal’s terms. They defer to the experts on the issue, making Secretary of Energy Moniz’s nuclear expertise crucial. But the broad public will neither view the completed deal as a big win nor as a big mistake by Obama. Most will wisely wait and see.  

Republican presidential hopefuls, many of whom sit in the Senate, apparently believe they can look POTUS-tough by blasting the deal, but doing so may simply deepen the main GOP vulnerability on national security since Bush-Cheney – an image of recklessness and war-mongering. And with Hillary Rodham Clinton the likely Democratic nominee, the GOP may have a hard time arguing the other side lacks the experience and toughness to stand up to America’s foes.  

Despite all the politics, the Obama administration ultimately should be able to preserve the Iran deal — especially since it only needs one-third support in one chamber to uphold the President’s promised veto if Congress votes to block the accord. When it comes to foreign policy, members of Congress tend to be cautious about taking steps that could expose their institution to clear blame for bad consequences, and actually scuttling this deal could well prove disastrous – potentially blowing up international unity on economic sanctions while also leaving Tehran free to ramp up its nuclear program. Rather than take such an institutional risk, Congress should lay down a strong record about the kinds of red lines they will be watching during the implementation process. For its part, the administration can help its case with Congress by showing strong support for the accord among military leaders and national security experts. It should continue to explain that the alternative here is not some mythical “better” accord with Iran, but rather war with Iran. And it should show that they have proceeded, not on the basis of trust in Tehran, but out of conviction that this strong international accord is the best bet to restrain Iran’s leaders’ hostile aims.  

Dr. Jeremy Rosner is a principal at Greenberg Quinlan Rosner Research. He was previously senior staff on the Clinton administration’s National Security Council, and senior adviser to President Clinton and Secretary of State Albright for NATO Enlargement Ratification.  

Get breaking news alerts and more from Roll Call in your inbox or on your iPhone.