The announcement of a historic deal with Iran curbing that country’s nuclear program makes it more likely that the 2016 election will be fought, at least partly, around a broad argument over the proper extent of U.S. international engagement as a means to solve the biggest future challenges we face.

It also means the presidential contenders will take sides around what has been called the Obama Doctrine: The idea that we should accept the limits of American power to enable us to solve these challenges on our own, even if that entails engaging internationally in ways that carry risks in their own right.

The details of the deal are listed right here. Congressional Republicans have already condemned it, while some key Senate Democrats — such as Tim Kaine of Virginia — are saying generally positive things while reserving judgment on the details. But the consensus this morning is that it will be very hard for Congress to block the deal from moving forward, at least in the short term. Because of the way Congress has structured its oversight mechanism, even if Congress disapproves of it, President Obama only needs just over one-third of one chamber to stick with his veto of that disapproval, which is very likely to happen.

Some of the major GOP presidential candidates — such as Scott Walker and Marco Rubio — have already pledged to undo an agreement with Iran, and crucially, they have said they will do so regardless of whether our allies want that deal to continue. Jeb Bush also condemned the previous framework.

By contrast, Hillary Clinton is likely to support the deal, though it remains to be seen how much hedging she’ll do along the way. Michael Crowley has a useful look at Clinton’s public statements on Iran, noting that she’s generally more hawkish than Obama but that she’s ultimately supportive of his diplomacy.

Thus, the argument that develops around the agreement may also take shape around the virtues and risks of international engagement. And this could join other issues to feed into a broader contrast, in which Republicans are opposing international engagement on multiple fronts — including Cuba and climate change (on which we may have an accord later this year). Meanwhile, Clinton may well embrace international engagement on multiple fronts, and use this contrast to cast the GOP as too inward looking and trapped in the past to confront the challenges of the future.

Peter Beinart argues provocatively that GOP opposition to the Iran deal is premised on a refusal to acknowledge the limits of American power. This puts Republicans in the position of opposing the deal mainly because there are risks associated with it, without offering any credible alternative. Obama described his international approach in similar terms in a recent interview with Thomas Friedman, who characterized the president’s position this way: America’s power may not be limitless, but it remains overwhelming, and the U.S. thus “needs to have the self-confidence to take some calculated risks to open important new possibilities.”

This doctrine also applies to engagement with Cuba and to an international climate accord (we don’t know whether other countries will keep up their end of the bargain). Beinart also suggests that the American mainstream may be more sympathetic to this worldview than pundits (who tend to give the Republican position the benefit of the doubt in such situations) think. I agree. While it’s hard to predict how the specifics of the Iran deal will play politically, Democrats should not fear this broader contrast. They should lean into it.

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* THE IRAN DEAL, SUMMARIZED: The Wall Street Journal has a quick summary:

At the heart of the agreement between Iran and the six powers — the U.S., U.K., Russia, China, Germany and France — is Tehran’s acceptance of strict limits on its nuclear activities for 10 years. These are supposed to ensure that the country remains a minimum of 12 months away from amassing enough nuclear fuel for a bomb. After the 10-year period, those constraints will ease in the subsequent five years.

In exchange, the U.S., the European Union and the United Nations will lift tight international sanctions on Tehran, a move that Western diplomats say could help Iran’s economy to expand by 7% to 8% annually for years to come.

Daniel Larison makes the case for the deal on these grounds: “This will limit Iran’s nuclear program more effectively than a decade of sanctions and coercive methods ever did, and it makes Iran’s acquisition of a nuclear weapon much less likely than any other available course of action.”

* OBAMA VOWS VETO IN IRAN FIGHT: The President’s statement this morning:

“This deal is not built on trust. It is built on verification. Inspectors will have 24/7 access to Iran’s nuclear facilities…I am confident that this deal will meet the national security interests of the United States and our allies. So I will veto any legislation that prevents the successful implementation of this deal. We do not have to accept an inevitable spiral into conflict.”

Republicans will argue that the deal is folly precisely because it requires us to “trust” Iran.

* OBAMA HOPES CONGRESS WILL BACK IRAN DEAL: The New York Times reports that Obama will likely get his way even if Congress disapproves of the deal, but he wants approval:

Mr. Obama’s chances of ultimately prevailing are considered high. Even if the accord is voted down by one or both houses, he could veto that action, and he is likely to have the votes he would need to prevail in an effort to override the veto. But he has told aides that for an accord as important as this one — which he hopes will usher in a virtual truce with a country that has been a major American adversary for 35 years — he wants a congressional endorsement.

But that would require Republicans — who have acted as if this deal is being negotiated by Obama and no one else — to endorse what they have already designated as Obama’s Capitulation To Iran.

* IRAN COULD BECOME ISSUE IN SENATE RACES: National Journal reports that Democrats think they can put Republican Senators on the defensive over their expected opposition to the deal. DSCC spokesman Justin Barasky notes that the public disapproved of Tom Cotton’s letter to Iran and will see opposition to the accord as obstructionist, adding:  “I think they’re the ones that are going to have to deal with the voters in a way that’s problematic.”

Of course, a number of Senate Dems could oppose the deal. Notably, Congress now has 60 days to review it, which means that Senators and Members will catch an earful from voters back at home during the August recess.

* CAN PELOSI SAVE IRAN DEAL? Bloomberg reports that the White House is relying on Nancy Pelosi as the firewall against Congressional disapproval of the deal. If the Senate musters 67 votes to override Obama’s veto of a Congressional vote against it, the deal still moves forward for now if more than one-third of Members of the House side with Obama.

Reminder: 150 House Dems have already signed a letter backing an Iran deal in general, which means House Dems likely would sustain a veto, though that’s not assured.

* LEFT GEARS UP TO DEFEND AGREEMENT: The statement on the accord just out from MoveOn:

“MoveOn members are going to fight like hell to defend it and to stop opponents from dragging the U.S. into yet another costly, deadly war of choice….We call on every member of Congress to support this agreement. Persuading senators and representatives to do so will be MoveOn members’ top priority over the next 60 days.”

If Congressional Democrats somehow end up helping Republicans tank the deal, you’d think there would be absolute hell to pay from the base….

* AND THERE’S BROAD SUPPORT FOR DIPLOMACY WITH IRAN: Aaron Blake reviews the recent polling and finds surprisingly broad support for diplomacy, even across party lines. This will not stop commentators from reflexively concluding that the politics of this will inveitably favor Republicans, of course.