...Opponents of the [Iran] deal, if they are to carry the day, need crisp talking points and plausible arguments; they need credible experts who will back up their position in congressional hearings, on opinion pages, and on TV and radio. And no organization has been better at providing this kind of intellectual firepower than the little-known Foundation for Defense of Democracies, a relatively small Washington think tank that is devoting itself to defeating the Iran deal.
During the last 18 months, FDD’s experts have testified 17 times before Congress in opposition to the interim and now final agreement. By contrast, experts from the Heritage Foundation, whose budget—$113 million in 2013—is more than 15 times the size of FDD’s, and which also opposes the agreement, have not appeared at all. Critics of the agreement from the American Enterprise Institute, whose budget is more than eight times as large, have testified only once.
In the wake of the agreement’s announcement, FDD experts have appeared on Fox News, CBS, CNN, PBS, and other television outlets at least 35 times to oppose it.
The Slate article goes on to note that pro-Israel think tank "is no longer a public relations group for Israel," and over the years, it has "become much more of a conventional think tank than an advocacy group."