In the read of the morning, Karoun Demirjian brings us the most comprehensive analysis I’ve seen yet of where the battle over the Iran deal in Congress stands, and the conclusion is a stark one: At this point, the chances that Congress will block the accord are very slim indeed.

Demirjian raises another striking possibility: It’s not out of the question at this point that opponents will fail to muster 60 votes in the Senate to stop the deal — which would mean that President Obama would not even need to veto the expected measure disapproving of the accord, sparing us a veto-override fight.

Here’s Demirjian’s math. According to the latest whip count, 31 Democratic or Dem-aligned Senators have either supported the deal or are leaning towards backing it. Another 12 Dems are genuinely undecided, and one (Ron Wyden) is leaning against it. Thus far, 56 Senators — 54 Republicans, plus Dems Chuck Schumer and Robert Menendez — are certain to vote to disapprove of it.

Sen. Robert Menendez (D-N.J.) said in a speech that he opposes the deal that would curb Iran's nuclear program in exchange for relief from economic sanctions. (AP)

To avoid a veto-override fight, supporters need 10 of those 13 up-for-grab Democrats. That might prove very hard, but it’s not impossible. My guess is that the following six Dems are the most likely to oppose the deal: Ben Cardin, Chris Coons, Ron Wyden, Gary Peters, Bob Casey, and Heidi Heitkamp. Opponents very well may get four or more of them (or persuade someone I’m missing) to go against it. That would give them 60 or more. But they might not get four of them. Which could mean no veto is necessary.

But let’s say opponents do get to 60, and a veto is required. Then the veto-override math kicks in, and it is very tough for foes. They need 67 Senators to oppose the deal. As Demirjian notes, that would require 11 of the remaining undecided Dems — which is to say, nearly all of them — to oppose the deal. And the math in the House is also trending towards the veto being sustained.

As I’ve said before, it is by no means a foregone conclusion that Democrats won’t help Republicans sink the deal. Huge expenditures on ads — or some kind of unexpected external event or revelation — could still shift the dynamic. But we’re now two-thirds of the way through August, which foes vowed to turn into a horrific political nightmare for Dems, and the math has only improved steadily for the deal’s supporters, making a veto-override appear less and less likely. And if the deal’s supporters do manage to avert even the need for a veto fight —  which I think is unlikely, but not impossible — that would be a very big defeat indeed for opponents.

Oh, and by the way, note this:

There is not a single Republican House member that has stepped forward to take a publicly supportive, or even receptive, stance toward the deal. And in the Senate, the only Republican  (Arizona Sen. Jeff Flake) who seemed open to embracing it decided against doing so over the weekend.

Remarkable.

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* DEMS LAUNCH NEW AD DEFENDING IRAN DEAL: The Dem-allied Americans United for Change is launching this new ad in a number of cities with large Jewish populations, claiming that “the same people that rushed us into war with Iraq want to sink the new agreement that would help stop war with Iran”:

The ad is backed by a $500,000 buy.

* TRUMP-MENTUM CONTINUES RAGING IN SWING STATES: A new Quinnipiac poll finds that Donald Trump is leading all his rivals among Republicans in Pennsylvania and in Florida, including Jeb Bush and Marco Rubio! In Ohio, Governor John Kasich leads, but Trump is in second and far ahead of all the others.

And yet, among registered voters overall in all those three states, Trump averages a favorability rating of 34-53.

* HILLARY’S NEGATIVES SOARING: The new Quinnipiac poll also finds that Clinton’s favorability ratings are 37-55 in Florida; 36-54 in Ohio; and 38-55 in Pennsylvania. The question is how much that will matter: Yesterday’s CNN poll found Clinton holding sizable leads over her GOP rivals despite being under water on her favorable numbers.

* TRUMP SURGE COSTING SCOTT WALKER BIG TIME: The New York Times reports that the Trump surge may be why Scott Walker is slipping so badly in must-win Iowa. Walker is telling supporters he’ll shake things up to prove that he, too, can take on the status quo:

Mr. Walker offered as Exhibit A an exchange he had had with a heckler just hours earlier at the Iowa State Fair: “I’m not intimidated by you, sir, or anyone else out there,” he had shouted, before turning to the crowd and saying: “You want someone who’s tested? I’m right here.”

Yep, smacking down hecklers is just the thing to arrest Trump’s momentum. That outta do it.

* KEEP AN EYE ON JOHN KASICH: The Post’s Robert Costa looks at how Jeb Bush is being squeezed in New Hampshire — and nationally — by an interesting dynamic: While Jeb is fending off attacks from Donald Trump, he’s got to worry about his more moderate flank:

Ohio Gov. John Kasich is moving swiftly to take advantage of the former Florida governor’s difficulties and make inroads with mainstream voters who otherwise would migrate to Bush.

Costa adds that in New Hampshire, “Bush has failed to consolidate the center-right coalition” that allowed Mitt Romney to win there in 2012. How Kasich exploits this will be worth watching.

* BATTLE OVER VOTING RIGHTS HEADED TO SUPREME COURT? E.J. Dionne assesses the battles over voting access that are unfolding in Texas and North Carolina, and indeed across the country, and notes:

You can bet that the Texas voting case or another in North Carolina, or both, will make their way to a Supreme Court that has already gutted the Voting Rights Act once in a 2013 decision written by Roberts. Will he do it again? And will voters in 2016 realize just how important a president’s power to name future Supreme Court justices is to the very right they will be exercising on Election Day?

The outcome of the North Carolina battle will have enormous implications. With Clinton leaning hard into the voting access wars, it is possible the makeup of the Court could become an issue on this front.

* AND JEB TRIES ARGUING ABOUT POLICY WITH TRUMP: With Trump proposing to deport 11 million undocumented immigrants and build a wall on the Mexican border, Jeb Bush pushes back at a town hall meeting, sort of:

“Look, the language is pretty vitriolic, for sure, but the hundreds of millions it costs to implement his plans is not a conservative plan.”

It seems rather optimistic on Jeb’s part to imagine arguing about concrete policy merits is the way to turn Trump’s supporters against him, but one hopes he’s right.