Credit Sen. Tom Cotton (R-Ark.) for raising the issue. Without a letter reminding the White House, Congress and the American people that a deal must be approved by the Senate in order to be binding, we might never have learned from Secretary of State John Kerry that “we are not negotiating a legally binding plan.” Oh, really?

For starters, a colleague reminds me that this was done with the North Korea Agreed Framework, negotiated by the very same U.S. diplomat, Wendy Sherman, who is handling the P5+1 deal.

What then do the Iranians think they are getting? No wonder the White House threw a fit. Cotton, as he did in an op-ed today, is reminding everyone of a simple fact: The deal goes away when Obama leaves office.

The critical role of Congress in the adoption of international agreements was clearly laid out by our Founding Fathers in our Constitution. And it’s a principle upon which Democrats and Republicans have largely agreed. In fact, then-Sen. Joe Biden once reflected on this very topic, writing that ‘the president and the Senate are partners in the process by which the United States enters into, and adheres to, international obligations.’ It’s not often I agree with former senator and now Vice President Biden, but his words here are clear. The Senate must approve any deal President Obama negotiates with Iran by a two-thirds majority vote. Anything less will not be considered a binding agreement when President Obama’s term expires in two years. This is true of any agreement, but in particular with the nuclear deal President Obama intends to strike with Iran.

This has several ramifications. First, it becomes the main issue for the 2016 campaign. Every candidate will have to signal whether he or she will walk away from any deal. George W. Bush walked away from the nonbinding deal with North Korea, and the next president can do the same with regard to a faulty Iran deal. Do Democrats want to run defending an Iran deal with a 10- year sunset? Good grief. Not even Bill Clinton could do that. Over 80 percent of Americans oppose just such a deal. And to boot, prominent Democrats are on record criticizing aspects of the deal.

Second, the Iranians cannot be sure they are getting more than a couple of years of sanctions relief; that may be all they want and enough to break the back of sanctions in Europe and elsewhere. But without Congress — just like Cotton said — they don’t get rid of sanctions permanently. By going it alone Obama may have undermine his only chance for a “legacy” on this issue.

Third, Congress should rethink its strategy. If it wants to leave the bulk of sanctions in place, it need do nothing more. If it wants to increase sanctions, as the Menendez-Kirk legislation envisions, lawmakers need to make certain they have enough votes to override a veto. And as for an up-or-down vote,  Congress can certainly deliver a sense-of-Congress resolution — which is not subject to a veto — but it alternatively can simply hang tight, see what happens in 2016 and refuse to abandon sanctions.

This is a pretty huge deal and should cause some serious rethinking about what the administration is doing. If all it can promise is, in effect, disruption of the sanctions regime during the lame-duck president’s remaining time in office, his conduct may undercut future presidents’ leverage, which will be badly needed to prevent Iran from getting to a nuclear weapons capability. Is this just about getting a piece of paper to wave around and leaving others to deal with the mess? It sure looks that way.

UPDATE (1:50 p.m.): Back in December, John Yoo and John Bolton addressed this issue: “Sole-executive agreements can only relay a promise by the current occupant of the Oval Office about the exercise of his own powers. The Constitution vests the president with authority as commander-in-chief to make decisions beginning and ending the use of military force. So, for example, an agreement that halted Tehran’s nuclear-weapons program but imposed no similar obligation on the United States likely would not be a treaty. … But agreements that extend beyond a president’s time in office or make long-term commitments of U.S. sovereignty must undergo the Article II treaty process.”

From a political standpoint, Hillary Clinton should hope a deal falls through so she need not defend it and can run on the promise she would be a tougher negotiator. Otherwise she’ll be stuck defending the indefensible.