"Especially notable is that Paul raised about triple the amount Obama received and about six times that of all currently-competing Republicans — Mitt Romney, Newt Gingrich, Buddy Roemer, and Rick Santorum — combined," the Paul campaign said in a statement last month. "Taken together, this means Dr. Paul raised approximately double the money from active military than all the candidates from both parties combined."

But Thorsen's in-uniform endorsement raised eyebrows among those familiar with military rules.

During the rally, the 28-year-old, stationed with a Des Moines-based unit, said meeting the Texas congressman was like "meeting a rock star."

"His foreign policy is, by far, hands down better than any other candidate's out there," Thorsen said.

Paul's campaign later said his appearance had not been planned. Thorsen was called to the stage by Paul during his address.

"I'm really excited about a lot of his ideas, especially when it comes to bringing the soldiers home," Thorsen told CNN. "I've been serving for 10 years now and all 10 years of those have been during wartime. I would like to see a little peace-time Army."