All Keven Cohen did was mention Republican presidential candidate Ron Paul on his radio program here before his phone lines began to light up.

The calls came from as far away as Colorado and Arizona. Ron Paul fans, listening via the Internet to Mr. Cohen’s conservative talk show, were eager to try to sway voters ahead of Saturday’s GOP primary in South Carolina.

The far-flung attention is unusual for Mr. Cohen’s show, “The Afternoon Drive,” which most often draws a local audience. “It doesn’t take a genius to figure out that we’re being monitored and that calls are being planted,” Mr. Cohen huffed.