Daniel W. Drezner is a professor of international politics at the Fletcher School of Law and Diplomacy at Tufts University and a regular contributor to PostEverything.

Casino magnate and major political contributor Sheldon Adelson waits with his wife Miriam, right, for Israeli Prime Minister Benjamin Netanyahu to address a joint meeting of Congress in the House Chamber in Washington March 3, 2015. REUTERS/Joshua Roberts

A few weeks ago Heather Hurlburt and I did a Bloggingheads segment about AIPAC’s decision to come out strongly against the Iran nuclear deal and whether it would affect the likelihood of a congressional rejection of the deal and override of President Obama’s veto. In the weeks since, even more money is lining up to oppose the Iran deal, as Catherine Ho reports for PowerPost:

The financial disparity between those opposing the deal and those supporting it is vast, at least where wealthy donors are concerned….

At least five groups and their affiliated organizations — such as a super PAC or charitable arm — that publicly oppose the deal received significant donations from the foundations of [Sheldon] Adelson, [Paul] Singer and [Haim] Saban since 2010, according to a review of the foundations’ tax filings and other publicly available information.

The pact’s supporters haven’t found as many prominent backers. At least three groups lobbying for the deal have received hundreds of thousands of dollars from the foundations of billionaire investor Soros and the Rockefeller family. They have also received significant contributions from Ploughshares Fund.

The New York Times’ Julie Hirschfeld Davis offers a similar account:

With an advertising budget topping $20 million and activists sent to meetings and town-hall gatherings with lawmakers around the country, [anti-deal groups] are working to transform what public polls show is a deep divide over the deal into sufficient opposition in Congress to block it.

So there’s a lot of money and interest group effort being deployed to oppose the deal. This will cause many liberals to rend their garments and tear their hair out and deplore the role of money and lobbying in politics.

But to this political scientist, all of this effort is puzzling. Ever since Nancy Pelosi and 150 House Democrats released a letter supporting the framework Iran deal back in May, I haven’t been able to see how opponents of the deal would win this vote. As my colleague Greg Sargent noted at the time:

The 150 Democratic signatories — which include Dem leaders like Nancy Pelosi and Chris Van Hollen — are significant. Here’s why: If a deal is reached that looks like the recently-announced framework, and the GOP-controlled Congress votes to disapprove of it, it’s now more likely that there will be enough House Democrats to sustain Obama’s veto of that disapproval legislation, allowing the deal to move forward.

Since the deal by expert accounts actually looks better than the framework agreement, those 150 House Democrats ain’t gonna budge for substantive reasons. Which means the only way that opponents will be able to override Obama’s veto is if they can apply enough political pressure on Democratic members of Congress to cause them to budge.

Now this is one of those interesting Political Science 101 tests of just what lobbying and money can actually do.  This is particularly true given that the polling on this question is ambiguous. As Sargent noted earlier this month:

I think the most reasonable takeaway from the totality of the polling is that a very large percentage of Americans doesn’t know much about the Iran deal. Thus, in the polls that don’t describe it and only offer a binary choice, the answers reflect dislike of Iran. By contrast, the polls that hint at the possibility of actual success in limiting Iran’s nuclear program — and only offer a binary choice — register more public support. In the first batch, people are saying, “we distrust Iran.” In the second batch, people are choosing “the thing that seems to make a nuclear Iran less likely.”….

[G]etting two-thirds of both chambers to override Obama’s veto would probably require a tremendous public backlash, since at bottom, most Congressional Dems are likely to be reluctant to sink Obama’s signature foreign policy achievement. And feelings may not be running all that strongly on this issue among much of the American mainstream.

So the big political science question is whether powerful interest groups like AIPAC, The Israel Project, and other organizations can shift public opinion sufficiently to move congressional Democrats not named Chuck Schumer.

The answer to that question is genuinely unclear. On the on hand, the polling is sufficiently amorphous enough that a concerted effort could sway public opinion.

On the other hand, if I had to bet money, I’d bet against the lobbyists and interest groups, for a few reasons. First, when it comes to foreign affairs, I’ll bet on public apathy over public engagement any day of the week and twice on Sundays. Second, this is going to be a partisan vote, and even this late in the term, congressional supporters of a president are loath to abandon him. Third, this is one of those rare moments when leadership matters, and it looks like the White House is going to be whipping hard on this issue.

So I expect this to play out pretty much like trade promotion authority: a close call, but Obama gets his way. The really interesting question is what this will mean for AIPAC et al if they lose. Interest group power is partly a matter of perception, the fear of going against an interest group with a reputation for winning. If AIPAC goes all in and loses, what will it mean for their reputation?