Health Secretary Robert F. Kennedy Jr. and his MAHA movement are out for payback, setting their sights on unseating a fierce adversary — Republican Sen. Bill Cassidy — in next week's Louisiana primary. Why it matters: Kennedy and his supporters view the physician-turned-senator as an avatar for the medical establishment they're determined to upend. The big picture: Cassidy, who chairs the Senate HELP Committee, has been openly skeptical of Kennedy's bid to reform health policy. After providing