Republicans have made no secret of their desire to sabotage multilateral negotiations over the Iranian government’s nuclear capabilities. That was the near-explicit purpose of Israeli Prime Minister Benjamin Netanyahu’s address to Congress last week. It’s what Senator Tom Cotton was getting at several weeks ago, when he said, “the end of these negotiations isn’t an unintended consequence of congressional action. It is very much an intended consequence.” And it’s supposedly the purpose of an open letter Cotton wrote—and that 47 Republicans signed—advising the Iranian government that the U.S. political system probably won’t sustain any deal they reach with the Obama administration.

“[W]e will consider any agreement regarding your nuclear-weapons program that is not approved by the Congress as nothing more than an executive agreement between President Obama and Ayatollah Khamenei,” the letter reads. “The next president could revoke such an executive agreement with the stroke of a pen and future Congresses could modify the terms of the agreement at any time.”

The hope, as Bloomberg’s Josh Rogin explained, is that “the Iranian regime might be convinced to think twice.” Put another way, Republicans want Iran to abandon negotiations and get to work on a bomb, thus inviting harsher measures. The administration and its allies in the non-proliferation community are predictably aghast, but their anger stems mostly from the Republican Party’s recklessness and its abandonment of political norms—which generally don’t include lobbying foreign governments to undermine a U.S. administration’s diplomatic undertaking.

In all the tut-tutting, though, I’ve yet to read a convincing case that Senate Republicans have advanced that goal even incrementally. The brazenness of their behavior has clouded the strategic question of whether this kind of intervention will actually have its intended effect. I don’t think it will. In fact, if you actually examine the incentive system the Obama administration is hoping to establish in a deal with Iran, it’s hard to escape the conclusion that Republicans have set back their own cause.

The letter itself is built on the presumption that Iranian negotiators don’t “fully understand our constitutional system.” That they’re unaware of the political obstacles any deal will face going forward, or that perhaps they’ve been misled into believing that Obama’s the only person in the U.S. government with any say over how a deal will play out.