Mississippi insurance commissioner Mike Chaney is in a tight spot. By law, he is required to implement Democratic President Barack Obama's healthcare overhaul. But as a Republican from deeply conservative Mississippi—one of 26 states that sued Washington over Obama's Affordable Care Act—Chaney is a target of critics who say he is betraying his party. Chaney and health officials in as many as 24 Republican-controlled states are working behind the scenes to set up insurance exchanges that provide a market for individuals and small businesses to shop for affordable health coverage.