The latest set of indicators:

1. Logic. Graham Allison, who originally made his academic reputation with Essence of Decision, his study of the negotiations that averted a U.S.-Soviet nuclear catastrophe in 1962, has another installment in his series of Atlantic essays on the details and implications of the nuclear agreement with Iran. This one is called “9 Reasons to Support the Iran Deal,” and it begins by reestablishing a crucial point about the deal’s critics.

None of them, from Israeli Prime Minister Benjamin “historic mistake” Netanyahu to U.S. Senator Lindsey “it’s a declaration of war on Israel” Graham, has yet risen to the challenge of offering a better real-world alternative. Better is something that would make Iran less likely to develop a nuclear weapon. Real-world is something that the Russians, Chinese, and other nations on “our” side would agree to demand from the Iranians, and that the Iranians would accept too. As the saying goes, this is the worst possible deal, except for all the alternatives.

2. A vote for. Representative Adam Schiff of California, the ranking Democrat on the House Intelligence Committee and “a moderate’s moderate,” tells The Atlantic’s Jeffrey Goldberg that he thinks the deal is in the best interests of both the United States and Israel, so he will support it. “At the end of the day, I could not find an alternative that would turn out in a better way than the deal,” he told Goldberg, making the essential real-world point. “The risks associated with rejection of the deal are quite a bit higher than the risks associated with going forward.”

[More votes for. Significantly, on Tuesday Democratic Senators Tim Kaine of Virginia, Bill Nelson of Florida, and Barbara Boxer of California signed on. On the WaPo’s site, Greg Sargent explains why these are bellwether declarations.]

3. A potential vote against. I take this headline from Politico as a good sign for the deal’s prospects in Congress:

How can a powerful Democrat’s opposition be a good sign? Because it suggests that Schumer has already calculated that the administration can do without his vote.

For rococo parliamentary reasons, the crucial voting showdown is still several legislative rounds into the future. First the Congress would have to pass a measure condemning the deal, which Republican majorities in both the House and Senate will certainly do. Then President Obama would have to veto the measure, which he will certainly do. Then the Congress would have to override the veto, which requires a two-thirds majority in both chambers—and this is what the Democrats, even in their diminished numbers, should still be able to block with some votes to spare.

Schumer doesn’t put it this way, but obviously he is hoping that one of those spare votes will be his. His life will be easier in many ways—in minimizing hassle during his upcoming reelection run in New York, and thus maximizing his efforts to help other Democratic candidates so that he has a chance of becoming Senate majority rather than minority leader—if he doesn’t have to spend time explaining away a vote for the deal to his conservative and AIPAC-aligned constituents. If the deal goes through despite Schumer’s opposition, people who support the deal won’t care, and those who oppose it can blame evil Barack rather than valiant Chuck.

But what if it came down to a single vote, so that Chuck Schumer himself would determine whether a Democratic president’s most important diplomatic effort succeeded or failed? Call me a cockeyed idealist, but in those circumstances I just can’t believe he would join Senators Cotton, Cruz, Inhofe, et al. in voting “no.” Thus any “Schumer-no” signal now may indicate his confidence that enough other people are going to vote “yes.”

4. Reality. The UN Security Council has already approved the deal, and by a 15-0 unanimous vote—hardly its norm on controversial issues. So has the European Union. Sample report, from Reuters: “‘It is a balanced deal that means Iran won’t get an atomic bomb,’ said French Foreign Minister Laurent Fabius. ‘It is a major political deal.’” The Russians and Chinese are moving ahead as if the deal is done, because from the world’s perspective it is.

The remaining forceful public opposition is from the unified GOP plus some Democrats, and the Netanyahu administration plus other Israeli figures. Even if they prevail, they cannot stop the deal and make five other countries reinstitute sanctions. Although you’d hardly know it from the U.S. debate, the opponents’ writ does not run to China, Russia, Europe, or Iran. All that a congressional “rejection” can do is ensure that the safeguards negotiated in the bill never take effect. As Graham Allison put it:

If the U.S. Congress rejects this agreement and proposes sending Secretary of State John Kerry back to the negotiating table, Kerry will most likely find no one else there. Partners who have negotiated and compromised over 20 months to achieve this accord will conclude that the U.S. government is incapable of making agreements. The international coalition will splinter and the sanctions regime will collapse, with Russia and China leading the way, but with France and Germany not far behind.

* * *

Netanyahu makes his case. Here is a late-update dose of reality. I have just now watched all of Netanyahu’s address on Tuesday to a webcast audience of 10,000 people, organized by the Jewish Federations of North America. By all means consider the case he makes.

The themes in Netanyahu’s opening presentation will be familiar to anyone following this topic. To wit: The deal doesn’t block Iran’s path to the bomb but “paves the path”; it will fuel and fund Iran’s international destructiveness; it will provoke a nuclear arms race in the region (which now has only one nuclear power); and it ignores Iran’s anti-Semitic commitment to Israel’s destruction, which obliges Netanyahu as Israel’s prime minister to consider this an existential threat. Also, “Iran can have its yellowcake and eat it too.”

To me the most interesting part of the presentation starts around time 14:30, when audience members ask Netanyahu: OK, so what’s your better idea? Judge for yourself, but I think his responses are so weak as to undercut everything else he says.

What’s his better idea? Well, first Netanyahu says that the U.S. should have been tougher from the start. But another questioner asks, in essence: That was then. What’s a better alternative now?

Against all evidence, Netanyahu’s better idea is that the United States should reject the deal—and then, on its own, significantly tighten sanctions on Iran. After the 15-0 Security Council vote, and the EU approval, and the Russian and Chinese preparations to resume business with Iran, the wisest course for the United States (according to Netanyahu) is to forget the previous negotiations and really crack down. Until now, Iran hasn’t given ground because it hasn’t felt enough pressure. But a new round of sanctions, really strong ones, will put the squeeze on Iran—and “after some initial erosion, the rest of the world will come around.” If you think I’m being unfair to the argument, check it out starting around time 15:20.

Is he kidding? Not at all. “It’s a no-brainer!” the prime minister explains. Since the U.S. economy is “40 times bigger than Iran’s,” it follows that the Europeans, the Russians, the Chinese, and others will soon see where their self-interest lies. They will realize that this deal was an illusion, they’ll call back their business missions to Iran, and they’ll slap sanctions back on too. Then, once Iran’s leaders recognize what they’re up against, they will stop bluffing and stonewalling. Instead they will accept the “good” deal that America should have been insisting on all along.

Maybe you find this analysis convincing. I do not. At all.

First, I challenge the prime minister to find any sane observer in China or Russia, or even England, Germany, or France, who thinks those countries would respond in the way he suggests. And second, I suggest that he consider the deep incoherence in his views of Iran. On the one hand, its leaders are so fanatically consumed with anti-Israeli hatred that they will countenance the destruction of tens of millions of their own people in a retaliatory nuclear strike from Israel, as long as they have the chance to kill as many Jews as possible. That’s why Iran is an existential threat. On the other, those same leaders are such canny cost-benefit pragmatists that they’ll fold and give up their vain nuclear plans, once they understand how much money the sanctions are costing them.

You can say one thing or the other—that Iran is a jihad state bent on Israel’s destruction (and America’s, as the prime minister points out), or that it will crack as soon as the financial cost goes up. You cannot say both, not with any respect for your audience.

But to be fair, I challenge you not to be charmed by the part from time 20:00 to 20:15.

* * *

This deal is going to take effect. Then a whole new set of challenges unfolds.