Ever since the Iran deal was announced, it has been widely presumed — by Republicans, and some neutral observers — that the battle over it in Congress will inevitably be a political winner for the GOP. The Iran debate just seems risky for Democrats — it involves negotiating with the enemy! — and Beltway punditry often assumes that debates over national security always favor Republicans, because, well, partly because Republicans are very good at saying so.

But in an interview with me, David Axelrod — the chief strategist of Barack Obama’s two successful presidential campaigns — made the opposite case. He said the Iran debate actually could favor Hillary Clinton and Democrats, and put the GOP presidential nominee in a politically untenable spot. That is, if Democrats prosecute it correctly.

“Broadly, I don’t think it’s at all clear that Americans are opposed to this,” Axelrod said. “Americans recognize that a verifiable agreement is a better option than war.”

“The key question here is, If you walk away from this, then what?” Axelrod continued. “It’s the responsibility of every single politician, Republican and Democrat, to answer the what’s-the-alternative question. And ‘let’s go to tougher sanctions’ is not a real answer.”

As many Democrats remain undecided about the substance of the deal, some also appear skittish about the politics of backing it. One exception has been Clinton, who spoke positively about the deal after it was announced. In so doing, she may have offered a template for how Dems should talk about it, hailing it as an “important first step” while stressing that “the agreement will have to be enforced vigorously, relentlessly,” an apparent nod to worries that Iran might try to cheat.

Nobody knows how the debate over the deal will play throughout the hot month of August, and both sides are gearing up to spend huge sums to pressure lawmakers back at home. It will also come up repeatedly for the presidential candidates. Asked whether it was reasonable for some Dems to be skittish about the politics of the deal, Axelrod said he thought Dem lawmakers were mostly worried about offending donors, not voters. And he suggested — perhaps counterintuitively — that its very riskiness could play Clinton’s favor.

“For her it’s very advantageous to stand by this agreement,” Axelrod said. “There is a perception of risk associated with that position. Her standing strong for it will strengthen her with the Democratic base. And I think it will strengthen her generally, because the picture of her taking on an issue that may have some risk, and standing by her principles on it, will help dispel some of the attacks on her.”

In the 2012 presidential race, Mitt Romney seemed to appreciate the public’s war-weariness, sometimes downplaying GOP hawkishness. But since then, the international outlook has changed, and Republicans won in 2014 partly by attacking Dems as weak on ISIS and Russia, which suggests perhaps they could win the argument over foreign policy in 2016, too.

Axelrod acknowledged the changed environment, but still said Americans would ultimately support diplomacy with Iran.

“In 2012 you didn’t have ISIS, Russia was more cooperative, it was a different environment,” Axelrod said. “But I still don’t think this means people are eager for military engagement with Iran. I think that the logic of a tough, verifiable agreement, as opposed to military action, is going to be the majority opinion in this country.”

Axelrod added that the Iran debate could end up hurting the eventual GOP nominee, who will be required by the base to promise to undo the deal during the primary — and then struggle to explain that position in the general.

“Iran is like the health care debate for Republicans,” Axelrod continued. “They’re filled with rage but not with ideas. There hasn’t been anyone who has articulated a generally viable alternative. They can get away with thundering outrage in the primary, but when you get to the general, you’re going to get scrutinized more closely.”

“The Republican nominee is going to be faced with, ‘okay, what are you going to do?'” Axelrod also said. “There is no surgical way to take out the Iran nuclear program. You’re talking about a major military commitment. So I think it becomes a risky proposition for the Republican nominee.”

But it’s not inevitable that the American mainstream will see the situation as nothing more than a choice between the Iran deal and war. Couldn’t Republicans muddy those waters and create the impression that there’s a third way?

“That is the challenge for Democrats — to expose the fact that there is no third way,” Axelrod said. “If Republicans muddy the waters, that’s a dereliction on the part of Democrats. There is no third way. The emptiness of that argument needs to be exposed repeatedly and aggressively.”