With Sen. Barbara Mikulski providing the deciding vote , President Barack Obama has won the fight over his Iran deal — sealing for now a key legacy item and preventing what would have been a catastrophic defeat for his presidency. Here are some key takeaways:  

1. AIPAC is one of Washington’s most powerful lobbying groups, but it’s no match for a determined Obama and the broader progressive movement inside the Democratic Party base, outside some strongholds in New York, Florida and a few other pockets. 2. Sen. Charles E. Schumer didn’t exactly put his considerable political muscle into what probably would have been a quixotic effort to kill the deal.  Just one other Senate Democrat has joined him in opposition so far — Robert Menendez of New Jersey. The powerful New York Democrat and presumed heir to Minority Leader Harry Reid, D-Nev., deeply angered the White House when he announced his opposition to the deal early on — with a passel of ex-White House aides openly questioning whether he could continue to lead Senate Democrats over his second act of apostasy (alongside his earlier contention that the Affordable Care Act was a political mistake). The success of the deal could cause that anger to subside a bit. And most of that anger was outside the Capitol; there have been no hints from his fellow senators that they are about to abandon their support for him. (Rep. Debbie Wasserman Schultz of Florida might not have the same luxury, though, if she ends up opposing the deal while chairing the Democratic National Committee. )  

3. For all the talk of Obama being aloof and unable to woo Congress, he’s had a remarkable record of getting his own party in line when push comes to shove. He remains the most popular figure in Democratic politics, and the White House pulled no punches, warning that opposing the deal would put the nation on a path to war.  

4. Opponents’ harsh rhetoric and apocalyptic ads opposing the deal succeeded in ginning up Republican opposition, but if anything, those tactics backfired when it came to securing the Democratic votes they needed for a veto override. It probably didn’t hurt the president’s whip count to have every Republican candidate trip over themselves to slam the deal the hardest, while the Democrats running all lined up behind it save for Jim Webb. Do you really want to be the lonely Democrat siding with Donald Trump and Ted Cruz et al against Obama, Hillary Clinton, Martin O’Malley and Bernard Sanders? (Not to mention Vice President Joseph R. Biden Jr., who has been extremely active on the lobbying front for the deal.)  

5. The White House probably held a winning hand once they succeeded in getting Congress to go along with the “resolution of disapproval” gambit for reviewing the Iran deal .  

At one point, remember, there was talk of getting a veto-proof majority to impose new sanctions against the White House’s wishes. If 67 Democrats and Republicans had held together, they could have passed a law and overridden the president’s veto on a law requiring explicit congressional approval. But the law crafted by Foreign Relations Chairman Bob Corker, R-Tenn., and ranking Democrat Benjamin L. Cardin of Maryland didn’t do that; it instead required Congress to override a veto to kill the deal.  

If Congress couldn’t find 67 votes to demand congressional approval of the deal, why would they be able to find 67 votes to kill it outright? The math was stacked against the deal’s opponents from the get-go.  

That, of course, had the right wing upset about the Senate giving up its constitutional prerogative to ratify treaties, which would have required 67 votes to approve.  

Congress gets to blame itself because of how the sanctions were written into law in the first place. As Corker repeatedly noted, Obama had the authority under existing law to waive the sanctions on his own. And without the Iran-review law, there was every expectation Congress wouldn’t get a say or a vote at all on the Iran deal.  

Resolutions of disapproval, meanwhile, are a particularly elegant way for Congress to avoid responsibility — with the same tactic deployed repeatedly to raise the debt limit. Most lawmakers get to say they voted no and the president gets what he wants anyway.  

6. Ernest J. Moniz helped seal the deal.  Nearly every Democrat backing the deal has pointed to Moniz, the energy secretary and nuclear scientist, as a persuasive voice detailing how the deal will shut down each of Iran’s pathways to a nuclear weapon — at least for the next decade. When The Associated Press broke the news that Iran will do its own inspections of the Parchin site suspected of being used in the development of nuclear weapons — although not the fissile material required for them — Moniz helped lead the pushback.  

7. The alternative wasn’t appealing.  Another refrain from Democratic supporters of the deal — and the White House — was that pulling out of the deal now would mean going it alone. Key allies other than Israel want the deal and warned lawmakers we’d be on our own if we pulled out. There’s also the political hit a veto override would have represented to Democrats writ large. What would it say if the Democratic Party helped nuke the key foreign policy of their president and all of their presidential candidates heading into an election year? That’s a nightmare political scenario Democrats won’t have to contemplate any longer.  

Correction Sept. 4, 4:52 p.m. A previous version of this article misstated the amount of Democratic presidential candidates who support the Iran Deal. One Democrat, Jim Webb, opposes the deal.  

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