Ramesh Ponnuru offers a very weak defense of the Senate GOP’s obnoxious Iran letter:

This letter, though, raises less serious issues. For one thing, it doesn’t convey any message that should come as a surprise to the Iranians. They were already presumably aware that Republicans (and some Democrats) don’t like the shape of the deal that the administration wants to make with Iran. They also knew that most of the Republican presidential candidates have been critical of the administration’s stance on the matter and promised to pursue a tougher policy if they win the 2016 election. Democrats have criticized the substance of the Republicans’ position. But it would be implausible to say it’s wrong in principle for a presidential candidate to promise a new foreign policy. If presidential candidates can “undermine” a president’s policy, why can’t senators?

Senate Republicans’ hostility to a deal with Iran is well known, but that doesn’t excuse the senators for their breach of normal behavior with respect to negotiations with another government. Members of Congress from the opposing party can and obviously do oppose the diplomatic initiatives of presidents, but they aren’t supposed to take it upon themselves to tell a foreign government that an agreement that the U.S. is negotiating with them is going to be broken as soon as the current president is out of office. It is especially obnoxious to communicate this to a foreign government while the negotiations are still taking place. Hawks in Congress are taking the odd position that they should give the president free rein in matters of war while insisting that they should be allowed to insert themselves into the conduct of diplomacy. Perhaps someone should write them a letter instructing them on their real constitutional responsibilities.

If the letter doesn’t “convey any message that should come as a surprise to the Iranians,” then there was no point in writing it or making it public. The best defense of this stunt that Ponnuru can make is that it was useless. The authors and signers of the letter must have thought they were telling the Iranians something the latter didn’t already know, and they were certainly hoping to influence Iranian decision-making. That is a highly unusual and very unwelcome innovation in Congressional meddling on a major foreign policy issue, and it is one that anyone interested in an effective U.S. foreign policy ought to reject. So far, the Iranian response suggests that Tehran isn’t going to be easily manipulated by the posturing of our Iran hawks, and so the sabotage attempt appears not to have worked as planned. Contra Ponnuru, the most important question is whether the letter was proper, and the answer is that it clearly was not.