Mike Huckabee says President Obama is using his nuclear deal to “take the Israelis and march them to the door of the oven.” Mitt Romney describes it as a “generational calamity.” And while polls diverge, one recently taken by CNN suggests the public wants Congress to reject the agreement by a 52 percent to 44 percent majority.

This is one of the pivotal foreign policy decisions of the decade, so let’s examine the arguments:

Obama didn’t deliver what he promised. For example, we wanted “anywhere, anytime” inspections, but we caved and got a complex system that allows Iran to delay inspections. And in the later years of the agreement, Iran won a significant easing of controls. As Jeb Bush put it: “These negotiations began, by President Obama’s own admission, as an effort to deny Iran nuclear capabilities, but instead will only legitimize those activities.”

The U.S. didn’t get all it wanted (and neither did Iran) in an imperfect compromise. True, we didn’t achieve anywhere, anytime inspections, yet the required inspections program is still among the most intrusive ever. Remember too that this deal isn’t just about centrifuges but also about the possibility that Iran will come out of the cold and emerge from its failed 36-year experiment with extremism. That’s why Iran’s hard-liners are so opposed to the deal; they have been sustained by the narrative of the Great Satan as the endless enemy, and conciliation endangers them.

You doves think that a nuclear deal will empower reformers in Iran and turn it once more into the pro-American and pro-Israeli power it was under the shah. But sanctions relief may just give this regime a new lease on life.

Iran’s people are perhaps the most pro-American and secular of those of any country I’ve been to in the Middle East. (On my last trip to Iran, I took two of my kids along, and Iranians bought them meals and ice cream, and served them illegal mojitos.) The public weariness with the regime’s corruption, oppression and economic failings is manifest. I would guess that after the supreme leader dies, Iran will begin a process of change like that in China after Mao died.

That’s speculative. The real impact of the deal is that it will unlock tens of billions of dollars in frozen assets and new oil revenues, giving Iranian hard-liners more resources to invest in nuclear skulduggery and in extremist groups.

True, but that will happen anyway. Remember that this agreement includes Europe, Russia and China as parties. Even if Congress rejects the agreement, sanctions will erode and Iran will get an infusion of cash.

This agreement is a betrayal of Israel. Once Iran gets its hands on W.M.D.s, it will commit genocide.

Iran is widely believed to have developed biological and chemical weapons back in the 1980s, and it hasn’t used those weapons of mass destruction against Israel. And what American officials find awkward to point out is that Israel is already a significant nuclear power with a huge military edge, which is why it has deterred Iran so far. If I lived in Tel Aviv, would I be nervous? Sure. But I’d be even more nervous without this deal, which reduces the chance that Iran will acquire a nuclear weapon in the next decade. That’s why five former U.S. ambassadors to Israel endorsed the accord. (It’s also notable that American Jews are more in favor of the agreement than the American public as a whole.)

Obama pretends that the alternative to this deal is war. No, the alternative is increased economic pressure until Iran yelps for surrender. As Marco Rubio puts it, “Give Iran a very clear choice: You can have an economy or you can have a weapons program.”

So we apply the same economic pressure that caused the collapse of the Castro regime in Cuba in 1964? The same isolation that overthrew the North Korean regime in 1993? The same sanctions that led Saddam Hussein to give up power peacefully in Iraq in 2000? Oh, wait.…

Look, even you admit that this is a flawed deal. So why risk it? As Rick Perry says, “No deal is better and safer than a bad deal.”

If the U.S. rejects this landmark deal, then we get the worst of both worlds: an erosion of sanctions and also an immediate revival of the Iran nuclear program.

We have a glimpse of what might happen. In 2003, Iran seemingly offered a comprehensive “grand bargain” to resolve relations with the United States, but George W. Bush’s administration dismissed it. Since then, Iran has gone from a tiny number of centrifuges to 19,000, getting within two months of “breakout” to a nuclear weapon. The point: Fulmination is not a substitute for policy, and a multilateral international agreement achieves far more protection than finger-wagging.

Diplomacy is rarely about optimal outcomes; it is about muddling along in the dark, dodging bullets, struggling to defer war and catastrophe for the time being, nurturing opportunities for a better tomorrow. By that standard, the Iran deal succeeds. Sure, it is flawed, and yes, it makes us safer.