Instead, Cotton’s snarky letter sparked a backlash not only from the president, the vice president, congressional Democrats and the foreign policy community, it shifted the debate from the substance of a deal to tactics that portray the United States as so woefully divided that its leaders are willing to circumvent and embarrass one another. The letter was especially tone-deaf because it came just days after Senate Majority Leader Mitch McConnell attempted to put Corker’s bill up for a vote — before the March 24 deadline for the framework of a deal — but pulled it after Democrats planning to vote for it accused him of using the issue for political gain.

This breach of protocol is hardly the first. Democrats, and other Republicans, have long interfered with the foreign policy moves of presidents from the opposing party. These 47 Republicans are not traitors, and probably didn’t violate the Logan Act of 1799. Moreover, President Obama’s refusal to engage Congress on the terms of the deal with Iran is wrong. Republicans concerned about the deal, and the Democrats who agree with them, are justifiably frustrated that they are being shut out. On Fox News Channel’s “On The Record,” Sen. John McCain (R-Ariz.) said of the letter: “Maybe that wasn’t exactly the best way to do that, but I think that the Iranians should know that, that the Congress of the United States has to play a role.”

This cheap mistake surely, in even a small way, jeopardized the odds of getting the strongest deal possible with Iran and, more importantly, making sure Iran — not the United States — shoulders the blame for failure to reach one.