In the first salvo of the 2016 Republican ad wars, a conservative group is about to unleash a seven-figure ad campaign targeting Senator Rand Paul for being out of step with the party on Iran, just as he launches his presidential campaign.

The Foundation for a Secure and Prosperous America, a 501(c)(4) group led by veteran Republican operative Rick Reed, will go live with its campaign against Paul on Tuesday, while the senator is in Louisville, Kentucky, announcing his presidential candidacy. The group will begin airing ads on broadcast TV, cable and the Web in several early primary states accusing Paul of being weak on Iran and tying him to the Barack Obama administration's Iran policy, which polls show is deeply unpopular among Republican voters.

"Paul supports more negotiations with Iran while standing against more sanctions that would hold the Iranian regime accountable. That's not a conservative position, that's Obama's position," Reed told me in an interview Monday. "His longstanding position on Iran and his agreement with Obama on Iran calls into question his judgment."

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The scale of the campaign is remarkable this early on in a primary fight, and reflects not only the depth of the hostility toward Paul's worldview among many conservatives but also the prominence of national security in the 2016 cycle.

This is not the first major campaign Reed has influenced from the outside. He was the architect of the 2004 "Swiftboat Veterans for Truth" campaign that attacked John Kerry's national-security record and credentials. His new campaign against Paul will be bigger than even that effort, he said.

"Foreign policy has the potential to be as big in this campaign as it was in 2004 or even greater," Reed said. "To me, given the state of the world, that's a good thing."

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Tuesday's ad will hit airwaves in states that are part of Paul's rollout, including Iowa, New Hampshire and South Carolina, Reed said. The millions committed to the early effort ensure that Paul's deviation from the Republican field on foreign policy will be among the top issues used to illustrate his alleged divergence from the Republican voting public.

Paul has been avoiding any comment on the Obama administration's announcement last week that Iran and the P5+1 powers agreed to a political framework in which Iran would receive sanctions relief in exchange for scaling back its nuclear program. All the other Republican contenders have come out against the deal, and former Texas Governor Rick Perry promised Monday to trash it if he is elected.

On Monday, after several days of silence, a Paul spokesman told Bloomberg:"Senator Paul will be watching closely and believes any deal must make clear Iran cannot acquire a nuclear weapon, allows for full verification and is approved by Congress."

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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.

If he tries to play both sides, the calls for him to clarify his Iran policy will follow him for as long as he is a viable candidate.

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Josh Rogin wrote this column for Bloomberg View.