Democrats have been outraged by 47 Senate Republicans ostentatiously trying to blow up negotiations with Iran with their "open letter" to Iranian leaders - essentially begging Iranian hardliners to blow up the talks on the Republicans' behalf. Senate historians could find no precedent for the party opposed to the President in Congress trying to blow up an international negotiation involving the United States in this way.
But in terms of practical outcomes, the main drama still lies ahead. The main drama in terms of practical consequences is still all about Senate Democrats, not about Senate Republicans. Without at least six Senate Democrats supporting them, Republicans cannot pass anti-diplomacy legislation in the Senate. Without at least thirteen Senate Democrats supporting them, Republicans cannot override a Presidential veto of anti-diplomacy legislation. Without the support of a substantial group of Senate Democrats, Republicans cannot blow up the talks. The key question in the wake of the unprecedented controversy around the Netanyahu anti-diplomacy speech to Congress and the Republicans' open letter to Iran is: which Senate Democrats will reward the Republicans who did these things by helping them try to blow up diplomacy?
The Obama Administration has known since 2010 that given 1) Republican control of (at least one house of) Congress, 2) the tremendous influence of the Netanyahu lobby with Congressional Republicans and 3) the apparent willingness of most Congressional Republicans to engage in partisan opportunism about almost anything, it would likely be an insurmountable challenge to get Congress to do anything to affirm diplomacy in the immediate wake of an achievable multilateral agreement with Iran. The multilateral negotiations with Iran always took this into account.
There are three things that the U.S. government can do to lift U.S. sanctions on Iran in the context of an agreement: 1) President Obama can lift sanctions on Iran that he imposed by executive action, 2) President Obama can waive sanctions on Iran imposed on Congress for which he has waiver authority, and 3) Congress can repeal sanctions legislatively. U.S. participation in multilateral negotiations with Iran has long assumed that in the context of an agreement, President Obama would do 1) and 2) on his own and leave pursuit of 3) until later - just as President Obama moved on his own to reform immigration policy, just as President Obama moved on own to ease the Cuba embargo, knowing that Congressional action would have to wait.
In the case of the Iran sanctions, it has been reasonably assumed that when an agreement has been in place for some time, with Iran obviously complying, with the temperature lower, with European companies going back into Iran and U.S. companies complaining that they are being cut out of market share in Iran by the Europeans, it will be easier to get Congress to repeal sanctions. And in any event, the sanctions that are really biting Iran are not unilateral sanctions imposed by the U.S. but multilateral sanctions imposed jointly with the Europeans. And those are going to go away in the context of an agreement, no matter what Congress says, because the Europeans and others are not going to comply with them no matter what Congress says in the context of a deal.
So the undermining of diplomacy that will finally matter - if it happens - will be that of certain Senate Democrats. The antics of the 47 Republicans will largely matter in the long run to the extent that they backfire relative to their stated purpose - to the extent that they help force a subgroup of Senate Democrats to stop threatening to enable Republicans and instead close ranks behind the President.
Since January 1, fifteen Senate Democrats (counting Angus King of Maine as a Democrat) have done at least one of three things that signaled that in certain circumstances, they might make common cause with Republicans to blow up diplomacy, although they would not necessarily do so. Ten signed the January Menendez letter promising that they would not vote yes on new sanctions before March 24, but threatening to do so afterwards; eight co-sponsored the Kirk-Menendez bill imposing new sanctions on Iran in violation of the interim deal, and seven have co-sponsored the Corker-Menendez "Congressional delay and review" bill, currently considered the main Senate vehicle for trying blow up the talks. (50 pro-diplomacy organizations, including MoveOn and Americans for Peace Now, just sent a letter to the Senate urging opposition to the Corker-Menendez bill.) Michael Bennet of Colorado officially co-sponsored the Corker-Menendez bill on Tuesday, the day after the 47 Republicans sent their anti-diplomacy letter.
Here are the 15 Democrats who have signaled since January 1 that they might help Republicans undermine the President and blow up diplomacy:
Bennet, Michael F. [D-CO]: Corker-Menendez
Blumenthal, Richard [D-CT]: Menendez 10, Kirk-Menendez
Cardin, Ben [D-MD]: Menendez 10
Casey, Robert P., Jr. [D-PA]: Menendez 10, Kirk-Menendez
Coons, Christopher A. [D-DE]: Menendez 10, Kirk-Menendez
Donnelly, Joe [D-IN]: Menendez 10, Kirk-Menendez, Corker-Menendez
Heitkamp, Heidi [D-ND]: Corker-Menendez
Kaine, Tim [D-VA]: Corker-Menendez
King, Angus S., Jr. [I-ME]: Corker-Menendez
Manchin, Joe, III [D-WV]: Menendez 10, Kirk-Menendez
Menendez, Robert [D-NJ]: Menendez 10, Kirk-Menendez, Corker-Menendez
Nelson, Bill [D-FL]: Corker-Menendez
Peters, Gary C. [D-MI]: Menendez 10, Kirk-Menendez
Schumer, Charles E. [D-NY]: Menendez 10, Kirk-Menendez
Stabenow, Debbie [D-MI]: Menendez 10
It's all about Senate Democrats, and, at this writing, these are the fifteen Senate Democrats who have indicated by their actions that they are most likely to undermine the President and help enable Senate Republicans to blow up diplomacy. You can urge your Senators to oppose the Corker-Menendez bill and the Kirk-Menendez bill here.