I’m watching with growing anxiety the bipartisan march in our national legislature toward derailing talks with Iran. And I’m wondering: is there any possible way to build a constituency for diplomacy?

Because here’s the thing. The antiwar left is overwhelmingly focused on villains at home. This isn’t a purely partisan thing: the left, after all, turned very hard against Lyndon Johnson, who was a more effective advocate for their domestic agenda than any prior president since FDR, or any president since—but obviously the left is going to have a quicker trigger when there’s a Republican in the White House. In a larger sense, though, the big problem is that the antiwar left is a negative force; it isn’t much good at ginning up enthusiasm for any particular action—which is what’s needed to shape the policy environment in advance of the kind of crisis that prompts talk of military action. This was Peter Beinart’s point in his recent piece about the failure of the antiwar left to pay attention to Iran.

Something similar is true on the antiwar right. The antiwar right, like the antiwar left, is much more exercised by adventurism by the opposing party, though there was some fringe dissent during both the Bush I and Bush II years. But the larger problem is that the antiwar right is, again, reactive, a negative force. It’s against wars that are “not in the national interest” or that involve “nation-building,” but again, that’s a negative perspective that only comes into play once there’s already a real prospect of conflict.

Moreover, both antiwar factions have difficulty advocating for diplomatic engagement for another reason. The antiwar left has fundamental doubts about the integrity of American power. But diplomatic engagement requires a comfort with that power, and understanding of its uses and its limits. The antiwar right, meanwhile, has fundamental doubts about the legitimacy of limits on national sovereignty and freedom of action. But diplomatic engagement, again, requires comfort with the architecture of international relations, which is buttressed all over with liberal internationalist structures of one sort or another.

As a consequence, it’s very difficult for the antiwar constituencies in the two parties (and outside of either) to work together for a foreign policy that is more restrained in its use of force. Which means that right now, both Democrats and Republicans in the Senate and the House of Representatives are pushing legislation that pretty much everyone involved in the diplomatic process understands is designed to make a diplomatic solution much less likely.

In the absence of a diplomatic solution, the arguments for military action will get louder and stronger. But the substantial majority who oppose war, and the large minority who oppose it fiercely, are basically having almost no effect on the debate over the diplomatic process.

I don’t know what there is to do about that. But it troubles me greatly.