The new Post/ABC News poll finds that there is majority support (56%) for the Iran deal, which includes support from a large bloc of Republican voters:

But Republicans at-large are a key reason for the deal’s continued popularity. The Post-ABC poll found more than 4 in 10 Republicans support the agreement (41 percent), while 54 percent are opposed. Even among conservative Republicans, one-third support a deal with Iran trading economic sanctions for a strict inspection regime.

Roughly two-fifths of Republicans across the country back the agreement, and they are almost completely unrepresented in Congress and in the 2016 presidential field. The striking thing is that there is such a high level of Republican support despite the absence of support for the deal from almost all pundits, politicians, and policy professionals on the right. If these Republicans are taking cues from their party leaders on this issue, they seem to be deciding to support whatever those leaders oppose. The third of conservative Republicans in favor of the deal might have offered one or more of the 2016 candidates a significant source of support in the primaries, but they have all lined up in opposition anyway.

A Cato/YouGov survey found a similar level of support at 58% for the deal. The breakdown of support by partisan affiliation was very similar:

Opposition to the deal is greatest among older voters, and there is majority support from all other age cohorts:

The Cato/YouGov survey also found that most Americans want Congress to let the deal proceed:

Americans also prefer Congress to allow such a deal to go forward (53%) rather than block the agreement (46%).

Both surveys find that the public is somewhat skeptical of the efficacy of the deal. This is consistent with previous surveys on this and other agreements. The public is generally in favor of pursuing negotiated agreements on disputed issues, and they are usually broadly supportive of the agreements produced by diplomacy, but they also typically doubt that the other regime will live up to its end of the bargain. The analysis of the Post poll finds that even among those that are “not so confident” there is strong support for the deal:

The key group are the one-fifth of the public who is “not so confident” a deal will work (22 percent). This group supports a deal by a more than 3 to 1 margin (69 to 21 percent), similar to their margin of support for the framework in March.

It is significant that this group isn’t sure that the deal will succeed, but nonetheless supports it by such a wide margin. That suggests that support for the deal is likely to hold and perhaps increase as it becomes clear that the deal is limiting and monitoring Iran’s nuclear program as intended.