Daniel Larison is not nearly outraged enough  by the Senate’s intrusion into the negotiations with Iran. What Senator Cotton and his colleagues are doing is deliberately trying to cripple America’s ability to conduct foreign policy. And, at least in terms of domestic politics, it may well work.
First of all, let’s dispense with the notion that there is any principled Constitutional question at issue whatsoever. Senator Tom Cotton does not believe for one instant that the President is incapable of entering into binding agreements with foreign governments, nor does he believe that Congress or subsequent administrations can dispense with such agreements without cost. We know this because he believes that the Budapest Memorandum  – which was not a treaty and was not submitted to the Senate for ratification – constitutes a binding promise to support Ukraine in its conflict with Russian-backed separatists, and that he believes failing to live up to this promise poses grave danger to the credibility of U.S. foreign policy generally. Here  is video of Senator Cotton saying as much.
So imagine, if you will, a Senate faction opposed to the Budapest Memorandum (perhaps out of fear that it signing it would oblige America to do precisely what Senator Cotton thinks it does oblige us to do) sending a letter to the Ukrainian president in 1994 alerting them that such an agreement would properly have to be submitted to the Senate for ratification, and might well fail, and that a subsequent president could revoke its guarantees at will. A hypothetical Senator Cotton-equivalent would readily understand that the purpose of such an effort was to obstruct the president’s ability to conduct foreign policy, and would be alarmed at the implications for the credibility of America’s commitments around the world.
Right? Of course right.
This has nothing whatsoever to do with the Senate’s responsibility with respect to “advice and consent,” and nothing to do with asserting the legislature’s proper role in foreign affairs – a role that the legislature continues conspicuously to abdicate. (The Obama administration has been in regular violation of the War Powers Resolution for years, but while individual senators and representatives have pointed this out from time to time, Congress has taken no action, and I don’t expect it ever will.) I don’t expect much from most of the crowd of signatories, but Senator Paul in particular should be excoriated for participating in this stunt. If he thinks this is a “constitutionally conservative” move, he needs to have his head handed to him by people who actually know what they are talking about.
Substantively, the view of the Republican leadership appears to be that any of America’s threats to use force, however ambiguous or slight, must be backed up vigorously for fear of a loss of “credibility.” Diplomatic agreements, however, are not to be taken seriously, because they may be discarded whenever a new leadership disagrees with what a previous administration agreed to. They affirmatively wish such agreements not to be credible, so that they are never entered into. And, funnily enough, if you cripple America’s diplomacy you’ll have lots of opportunities to demonstrate the “credibility” of America’s threats to use force. Which is exactly the goal – because such situations play to the GOP’s strengths as a brand.
And unfortunately, the Republican leadership may well be able to achieve their goals. Not internationally – I doubt the Iranians did more than roll their eyes at this stunt – but domestically. It turns out to be relatively easy to manipulate the public into supporting a more aggressive foreign policy. If talks with Iran fail (which they might have done regardless), it is vanishingly unlikely that the American people will blame the GOP leadership in any way that matters. On the contrary: if the talks fail, the country will be more supportive of a more aggressive stance toward Iran, which will redound to the benefit of the GOP generally and its more hawkish members in particular. So long as that’s the electoral dynamic, there are literally no disincentives for this kind of outrageous behavior.
To paraphrase the immortal words of Senator McConnell, the negotiations with Iran may prove to have been a hostage worth shooting.