Some observers feel profoundly uneasy about both “talking and threatening.” This was a common concern during Richard Holbrooke’s far more aggressive—and successful—“talk and bomb” strategy with Slobodan Milosovic. Yet, in many contexts, such a two-sided negotiating approach is commonplace and often necessary. Without “threats”—filing a lawsuit, holding a strike vote, or buying shares in a target company—genuine desire for a negotiated resolution will often get nowhere.

A bit of perspective relative to these fairly mild examples: the Iranians, active backers of Hezbollah and Assad, have arguably sought, sometimes covertly, the most destructive weapons on the planet, whose acquisition would almost certainly lead to highly dangerous regional proliferation. Relative to these stakes, how worried should P5+1 be about Iranian sensibilities versus Iranian assessments of tangible interests?

One fair critique of the “pre-negotiated sanctions” approach is that the president has already and repeatedly issued such sanctions threats. So have his Secretary of State and other senior administration officials. For example, beyond references to military options, President Obama threatened in December 2013: “if negotiations fail . . . new and harsher sanctions will be put into place.” As recently as January, Deputy Secretary of State Blinken testified that “should Iran refuse a reasonable deal . . . the Senate and House could impose additional measures in a matter of hours. The Administration would strongly support such action.”

Notably, if explicit threats of harsher sanctions would truly wreck the atmosphere, these ominous administration statements would have already scuttled the interim talks. However, the real issue is not the atmospheric implications but how credible the Iranian leadership perceives threats of dire consequences if an acceptable deal is not reached by a clear deadline.

While the administration has stated its willingness to intensify sanctions in the event of no deal, its actions to date—visible to the Iranians and the Congress alike—have mainly been to vociferously head off all such measures while urging repeated extensions of the interim deal.

In particular, the administration pulled out all the political stops to successfully defeat the Menendez-Kirk sanctions bill in 2014, and again acted aggressively to forestall the 2015 version of this bill. These actions, taken at considerable domestic political cost, have certainly signaled to its Iranian counterparts a willingness to negotiate seriously. Yet they may have come at a cost in administration credibility to impose and implement new sanctions.

After all, solemn pronouncements by multiple U.S. administrations—not just that of president Obama—and their allies about firm deadlines lack credibility given years of steadily receding “red lines.” Over decades, the Iranian nuclear program advanced to points that the United States and its allies first declared to be unacceptable . . . and then, when Iran crossed those red lines, effectively accepted as a fait accompli.

Of course, the Iranians fully understand the overwhelming likelihood that the Republican Congress would pass a sanctions bill if negotiations fail—and quite likely beforehand. That does not, however, mean that new sanctions would hit Iran. In the interest of “giving further negotiations a chance,” the president could still veto such a bill and, if his veto was overridden, could drag his feet in implementation.

If the Iranians, let alone the Republican Congress, doubt that yet another red line means much, how could this threat be made more credible? Clearly, the Congress and administration must visibly be on the same page on this issue. A pre-negotiated Executive-backed sanctions bill with a Congressional commitment to pass it on a certain date coupled with a very public and personal presidential commitment to sign this specific bill by this specific date under these precise circumstances would remove much of the ambiguity.

This approach should permit the administration to have it (most of) both ways: a continued and evident willingness to negotiate seriously, by holding off Congressional sanctions, while setting a real deadline for higher costs to Iran in the event no deal is reached.

Sanctions opponents often claim that, without negotiations, the P5+1 would face two very unpalatable alternatives: a nuclear-capable Iran or war. Yet, if no satisfactory deal with Iran emerged by the deadline and more stringent sanctions do go into effect, this would not necessarily spell the end of negotiations facing the P5+1. If anything, the Iranian regime would have an even greater incentive toward a deal. If the parties decided to keep pushing forward, which seems likely, the tighter sanctions would function as a higher cost inducement for Iran during continuing talks.

Why would a Republican Congress conceivably grant permanent sanctions relief authority to a President whom it doesn’t trust?

A central Iranian complaint about P5+1 proposals thus far has been the inability of the United States to deliver on sanctions relief promised at the bargaining table. Currently, President Obama can at most offer Tehran temporary executive branch waivers of some sanctions, which could easily be revoked by a later administration. This limitation greatly reduces Tehran’s incentive to make the kind of irreversible cuts in its nuclear program sought by the P5+1 as well as the Congress. (This Iranian complaint also applies to sanctions imposed by Europeans and the U.N.—which should be handled analogously to what’s recommended here.)

How might president Obama gain such authority from a suspicious and hostile Republican Congress? Suppose the president does an about-face and actively works with the Congress on the “pain” side of the ledger. Suppose he is credibly willing to impose more stringent sanctions rather than fighting them, as has been the case until now.

While not quite Sadat to Jerusalem or Nixon to China, such moves by the Obama Administration should heavily assuage Congressional concern about a president too eager to make almost any nuclear deal. The mechanisms proposed above as part of the sanctions bill would make it very difficult for the president to accept an inadequate deal that leaves Tehran with an exercisable nuclear option. Indeed, the president should be seen by Iran and the Congress alike as much less willing to even consider a “bad” deal. This should increase his bargaining leverage.

And a real deadline would then exist with the almost certain passage of such a bill, diminishing Congressional fears of indefinite extensions of the already-twice-extended interim deal.

These elements of “downside protection” should be linked to a Congressional grant of authority to the president to permanently lift key sanctions on a phased basis if an Iranian nuclear deal meets certain tough criteria and if Tehran scrupulously observes its implementation commitments. It is hard to even imagine such a Congressional grant to the president on the “carrot” side without an Administration commitment to sanctions.

If the president had such authority, credibly offering a more valuable deal to Tehran could, with skillful diplomacy, elicit greater Iranian concessions and a better agreement from a P5+1 viewpoint. Ironically, such an agreement could also be more to Congressional liking. If this happened, Tehran could enjoy more permanent benefits; if not, sharper sanctions, the result of an explicit executive-legislative deal, would await.

Of course the Congress might fear that the administration would be outnegotiated, just “giving away” more permanent sanctions relief in return for little. The safeguard against this outcome or other “bad deals,” however, lies in the bill’s tough criteria that a nuclear deal must meet to avoid sanctions.

On balance, this approach offers the prospect of a president with every incentive to hang tough with Iran as well as the ability to offer inducements to that country in return for a more satisfactory nuclear deal. This might be sufficient for the Congress and the Administration to find agreement. It would sharpen sticks and sweeten carrots while imposing a real deadline. This course of action, while devilishly tricky to negotiate, should materially improve the prospects for a better deal with Iran.

James K. Sebenius is the Gordon Donaldson Professor of Business Administration at Harvard Business School, Director of the Harvard Negotiation Project, and member of the Iran Working Group at the Belfer Center at Harvard’s Kennedy School.

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