Over the past few months, Paul has been slowly but surely adjusting what critics call his isolationist worldview, toward one that he describes as realist. But that, too, is troubling to many conservatives, who don’t trust his recent turn towards a more muscular foreign policy.

“Part of the purpose of this campaign is to hold him accountable and to remind people explicitly about what he has said in the past,” Reed said. “The whole campaign we are about to undertake signifies the deep mistrust among conservatives about Paul and his views on Iran.”

Reed declined to disclose his group’s donors. As a registered nonprofit, the group doesn’t have to reveal its funding sources. But there has already been reporting that several big-dollar Republican donors are planning to open up their checkbooks to attack Paul on foreign policy, including as pro-Israel billionaire Sheldon Adelson.

The ads threaten to disrupt Paul’s launch by forcing him to choose between appeasing his critics or staying true to the libertarian base that brought him this far.