Rihanna's song, "Don't Stop the Music," was played on Sunday at Trump's rally for U.S. Senate candidate Marsha Blackburn br in Chattanooga, Tenn. On Instagram, Rihanna endorsed Democrat Andrew Gillum in Florida's governor's race. Last week, Pharrell Williams sent a cease-and-desist letter to Trump for playing his song "Happy" at a political rally. Most venues for campaign events have a blanket license from a performance rights organization in place.