Few presidents have promoted a policy with more unbridled self-confidence than Barack Obama has promoted his nuclear deal with Iran—and, in this case, the swagger is justified.

In a speech Wednesday morning at American University, he spent as much time deriding his critics as defending the deal, dismissing them as “wrong,” “ignorant,” “selling a fantasy,” or locked in “a mindset” that prefers war to diplomacy.

He kept it up a few hours later at a 90-minute session with a small group of columnists, in the Roosevelt Room of the White House, rebutting each of the critics’ arguments—this one “defies logic,” that one “doesn’t make sense,” yet another “seems unanchored to facts.” All in all, they “don’t hold up.”

“Of all the foreign policy issues that I’ve addressed since I’ve been president,” he summed up his case for the deal, “I’ve never been more certain that this is sound policy, that it’s the right thing to do” for the United States and its allies.

The case has been made countless times, in Slate, many other publications, and, in point-by-point detail, in Obama’s speech this week. What was most interesting about that speech—and the session that followed—is that the president’s primary aim is to stiffen the arguments and energize the activism of the deal’s supporters, with a secondary goal of nudging the neutral and undecided into the column of supporters. One thing he’s no longer trying to do is to convert the opponents, who, locked by justifiable anxieties or irredeemable biases, have shown that they’re unswayable by logic and uninterested in the facts.

At the White House Correspondents’ Dinner in April, Obama said that, after the midterms, people asked him whether he had a bucket list. “Well,” he recalled replying, “I have something that rhymes with bucket list …” To illustrate the point, he said, “Take executive action on immigration? Bucket! New regulations? Bucket!” And now, he seems to be jotting a new item on the list: Iran nuclear deal? Bucket!

He can’t do this one entirely on his own. Though the deal is not legally a treaty (but rather a seven-nation political arrangement, backed by a U.N. Security Council Resolution), members of Congress did insist on a role for themselves, allowing 60 days from the deal’s signing to vote on it, up or down. The House and Senate, both controlled by Republicans, are likely to vote it down; but Obama has said he’d veto that motion—and few believe the GOP can muster the two-thirds majority needed to override the veto.

That’s the task, then, that Obama has placed before him in Washington’s polarized politics—hanging on to enough Democrats to sustain the veto. “If I presented a cure for cancer, getting legislation passed to move that forward would be a nail-biter,” he said at the session with columnists. “So my main concern is simply to be able to implement the deal … I’m less concerned about the point spread.”

At that session, he elaborated on the argument that has most riled his critics—that the only ways to keep Iran from getting a nuclear weapon are to approve the deal or eventually go to war. Critics have denounced this claim as unfair fearmongering. But Obama told the columnists that he was only laying out “the dictates of cold, hard logic.”

The logic is this: Iran was driven to the negotiating table by the pain of international sanctions; European and Asian leaders agreed to impose sanctions, at considerable economic cost to themselves, only after being persuaded that doing so might lead to a deal that stopped Iran from building a bomb; we now have that deal. Those who want Congress to reject it seem to believe that our diplomatic partners will follow us in reimposing the sanctions and forcing Iran to accept a “better” deal. In fact, Obama rightly said, this is “fantasy.”

Instead, if Congress rejects the deal, the sanctions will collapse, and Iran will resume its nuclear program—rather than halting, slashing, and subjecting it to international inspectors, as the deal would have required. Then, at some point, Obama predicted, “some of the same voices who were opposed to the deal would insist that the only way to stop Iran from getting a nuclear weapon is to take strikes. And it will be framed as limited military strikes, and it will be suggested that Iran will not respond, but we will have entered into a war.”

In other words, without the deal, Obama said, “we’ve sort of run out of options” to keep Iran’s nuclear program bottled up. “No one has described to me what remaining leverage that we have.”

Or, if the Iranians don’t go nuclear immediately, Obama went on, they could weaken us in other ways. One scenario he laid out:

They could say, “We’re going to go ahead and abide by the deal, despite what the U.S. Congress says,” and put our partners—Russia, China, as well as the Europeans—on notice that they’re ready to do business … It’s hard to conceive of Russia and China not taking full advantage of that—not only because of commercial purposes, but because of the enormous propaganda boom that it provides them at a time when the entire story they’re telling around the world is that U.S. hegemony is over, that we need an entirely new set of global institutions that are more reflective of the balance of power. And in that scenario, then Iran is going to get some of that sanction relief anyway, and our credibility, in terms of now being able to exercise any influence

http://www.slate.com/articles/news_and_politics/war_stories/2015/08/president_obama_is_completely_confident_in_the_iran_deal.single.html