Peter Bergen is CNN's national security analyst, a vice president at New America and the author of "United States of Jihad: Who Are America's Homegrown Terrorists and How Do We Stop Them?" The views expressed in this commentary are solely those of the author.

(CNN) On the campaign trail, Donald Trump was clear about his view of the 2015 Iran nuclear deal , which delays the Islamic state from acquiring nuclear weapons for more than a decade in exchange for the lifting of draconian US-led sanctions on Iran.

As president, Trump has carried on the drumbeat of criticism of the deal and hinted that he is about to take a major step on it. Trump can try to rip up the deal by "decertifying" that Iran is compliant within the terms of the agreement and have the Republican-controlled Congress act on it, for instance, by imposing new sanctions on Iran.

Trump reportedly plans to decertify the agreement by October 15, which is one of the regular deadlines for the continued certification of the nuclear deal.

But this move may be the foreign policy equivalent of trying to repeal and replace Obamacare, another key campaign Trump promise that ultimately he has not been able to deliver. In February of 2016, Trump tweeted , "We will immediately repeal and replace ObamaCare - and nobody can do that like me. We will save $'s and have much better healthcare!"

Just before the election, Trump promised the repeal would come "very, very quickly."

Trump has since encountered the reality that Obamacare is now supported by a slim majority of Americans, according to a poll released in June, while the various Republican alternatives to the Affordable Care Act that emerged during recent months are generally unpopular.

Similarly, with the Iran nuclear deal -- which Trump has called "terrible" and "the worst deal ever negotiated" -- the facts aren't going along with the President's promises. Secretary of Defense James Mattis testified just this past week that it is in America's national security interest to remain in the agreement.

The International Atomic Energy Agency has also repeatedly found that Iran is complying with the nuclear deal.

So if it's hard to make the case that the deal isn't working, why else would you tear up this agreement?

This is reminiscent of the fix that Trump and many of his fellow Republicans got themselves into when they kept saying that Obamacare was disastrous, but had no better plan to proffer.

Of course, Iran operates in other ways outside of the nuclear deal that are inimical to American interests, and indeed the interests of other countries, for instance, by propping up the Bashar al-Assad regime in Syria and supplying weapons to the Houthi rebels in Yemen. But the nuclear deal wasn't meant to fix Iran's regional meddling, irritating as that may be. Its goal, rather, was to ensure that Iran doesn't acquire nuclear weapons, which would then set off a regional nuclear arms race in the Middle East where Saudi Arabia would quickly follow suit.

Also, wouldn't an Iran armed with nuclear weapons behave worse than a non-nuclear-armed Iran? Just take a look at the behavior of North Korean dictator Kim Jong Un, whose antics on the world stage only get attention because he has nukes. Without nukes, Kim would simply be irrelevant. (North Korean GDP is $16 billion , which is considerably less than that of Vermont , which at $30 billion GDP is ranked last out of the 50 American states in terms of economic output.)

New sanctions?

Sure, the United States could try to unilaterally impose new sanctions on Iran. These wouldn't be nearly as effective as the previous US-led sanctions that involved many other countries and forced Iran to the negotiating table to ink the nuclear deal. This time around, the US would not have the support of other major Western powers to sanction Iran.

And to what end would the new sanctions be aimed, since critics of the deal haven't explained what would replace the current agreement? Then there is the inconvenient fact that Iran will not renegotiate the nuclear agreement. Similarly, Britain, France, Germany and Russia , which also negotiated the deal alongside the United States, have made clear that they want the deal to remain in place.

Finally, in Congress there may not be the 51 votes needed to overturn the agreement by imposing new sanctions on Iran. Republican Sens. Jeff Flake and John McCain of Arizona, and Susan Collins of Maine, for instance, all might vote against sanctions that would effectively end the agreement.

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Meanwhile, Sen. Bob Corker, the powerful head of the Senate Foreign Relations Committee, is in a well-publicized spat with Trump, who has taken to Twitter to denigrate him. Corker has little incentive to help Trump out on the Iran deal.

This could end up looking a lot like the failed effort to repeal Obamacare.