Allies of Sen. Rand Paul, R-Ky., in Iowa have begun raising questions about whether Sen. Ted Cruz, R-Texas, qualifies for president under the Constitution, according to an in-state political operative who supports the Texas lawmaker.

“They’re scared and they now keep bringing up the eligibility issue,” Jamie Johnson told the Washington Examiner. Johnson was coalitions director for Rick Santorum’s campaign during the 2012 Iowa caucuses, but he hopes Cruz wins the Republican nomination in 2016.

“They are hitting the eligibility issue hard,” Johnson said. “They’re using third-party sources, though; they don’t want it tracked back to Campaign for Liberty [an organization that grew out of Ron Paul's 2008 presidential bid].”

Update:  "Campaign for Liberty is not pushing this issue and this claim is complete nonsense,” communications director Megan Stiles told the Washington Examiner in response to Johnson. “Campaign for Liberty is a non-partisan grassroots lobbying organization and we do not support, oppose, or endorse candidates for office.”

Paul and Cruz have not clashed personally, but their respective treks to Iowa — home of the presidential primary season’s first election — suggest the Senate allies are on a collision course.

Johnson said that Paul’s supporters have grown wary of Cruz in light of his well-received speeches before Iowa social conservatives in July and August.

Cruz, born in Canada to an American mother and a Cuban father — he released his birth certificate to the Dallas Morning News Monday — maintains that he is a “natural-born citizen” under the Constitution and eligible to run for president.

“Sen. Cruz is a U.S. citizen by birth, having been born in Calgary to an American-born mother,” Cruz spokesman Sean Rushton said in a statement to the Washington Examiner's Byron York.

Johnson, who serves on the Iowa Republican Party State Central Committee, didn’t provide direct evidence that the whisper campaign is underway, but invoked his interaction with Paul’s supporters in the Iowa GOP. "How do I know? because I talk with them,” he said. “I look at their Facebook posts and their Twitter [feeds].”

Neither Iowa Republican National Committeewoman Tamara Scott nor former Iowa Republican Party Political director Craig Robinson has heard about Campaign for Liberty pushing the eligibility question — “You’re kind of looking to create a rivalry that’s not there right now,” Scott replied when the Washington Examiner asked about the issue.

Robinson has found, though, that Iowa political reporters are interested in Cruz’s eligibility. "I’ve only really heard that from some reporters in Iowa, I’ve not heard that from those who are in those camps; I’ve not heard that directly,”  Robinson said. While allowing for the possibility that Paul supporters are pushing the story to Iowa press, Robinson explained that political reporters who have asked him about the eligibility question think it stands as Cruz’s “biggest hurdle” in the state.

Jeff Shipley, a legislative director for Campaign for Liberty who also serves with Johnson on the State Central Committee, agrees that the topic could be an impediment, though not a major one. (Updated below.)

“If you’re going to call yourself a true constitutionalist, well, it’s right there in the Constitution,” Shipley told the Washington Examiner during a phone interview. “Obviously, that’s something Mr. Cruz needs to address, that he’s eligible for the office.” Shipley doesn’t think that’ll be difficult.

“With the legal documents, it’s all language, and he’s a very competent lawyer, so I’m sure he can get around it,” he said.

He also addressed the claim that Campaign for Liberty is casting doubt on Cruz’s eligibility. “There probably are some Senator Paul supporters that feel threatened by Senator Cruz, and they may be saying some things, but I think that’s just kind of petty nonsense — I don’t think it’ll amount to much,” Shipley said, noting that he hadn’t heard any Campaign for Liberty people making the argument.

“In terms of [Campaign for Liberty], the organization is very diverse and it’s just individuals, just like anything else, so I’m sure there’s some people saying some things, but, I’m not saying anything — like I said, I don’t really care — and I don’t expect it to really hurt Senator Cruz that much in any way,” he also said.

Rand Paul refused to fan the flame when he was asked about Cruz’s eligibility. “You won’t find me questioning his eligibility,” Paul told CNN last week. “I decided a long time ago I wasn’t going to be a birther for Democrats. I’m not a birther for Republicans.”

Certainly, there’s no open war between Cruz and Paul. The Republican Party of Iowa, which is largely dominated by Paul supporters, invited the Texas senator to headline the Ronald Reagan Commemorative Dinner in October.

That could change, though. “I could see a scenario where Ted Cruz is Public Enemy Number One should they both decide to run,” Robinson said.

Update: Shipley is a former district coordinator for Campaign for Liberty and current legislative committee chairman for Liberty Iowa PAC, another group that spun out of the Ron Paul presidential campaign.