"Being a slight libertarian myself, I agree with a lot of his issues," said Leighton Lord, a well-connected Columbia attorney. "But I am also a practical business guy. You can't maintain those hard-line libertarian views and be a chief executive. My gut is that Rand Paul is not one of those gets-things-done guys."
Stafford, the Paul adviser, said he's heard similar worries from potential supporters before, going back to the 2010 campaign in Kentucky when Paul would meet with Chamber of Commerce-types in Louisville and Lexington.
In later fundraising swings around the country, in tony locales like Silicon Valley and Manhattan, Stafford said Paul has used a personal touch to soothe fretful donors who just don't think he can win.
"The best part about Rand is you put him in the room with them and they become way less skeptical," he said. "He is a smart, reasonable person and I don't know that they are expecting the person that they meet. They will walk out, almost to a man, less skeptical. That's why we go to these things. That's why we do GOP events and not just activist events."
In a state with eight military installations, Paul has the added burden of convincing the South Carolina establishment that he won't push American foreign policy in an isolationist direction that could affect the livelihoods of thousands of veterans and military families.
Paul's national security views are leavened by his fidelity to protecting personal liberties. He fiercely opposes drone strikes and military intervention overseas, and he has condemned the recently revealed NSA surveillance program -- positions that put him at odds with South Carolina's hawkish Sen. Lindsey Graham, a reservist in the state's Air National Guard.
"There are some mainstream Republicans who are concerned that people who come from Paul's side of the party do not stand for strong national defense," said Cahaly, the Republican consultant. "He needs to make clear, especially in South Carolina, which is full of vets and people who support the military, that he is not a threat to them."
Lee Bright, a state senator who endorsed the elder Paul in 2012, argued that Rand Paul's views are "obviously more mainstream" than his father's.
But even if Paul can't persuade GOP elders to back him in a presidential campaign, he predicted, they might be able to persuade themselves.
"Keep in mind that the establishment always seems to gravitate toward a winner," Bright said. "If he is a front-runner, the establishment will find a way to support him."