The future of Truman Medical Centers, a two-hospital safety-net system here, depends on the state legislature—and no one understands that better than its new chief executive, Charlie Shields. Mr. Shields, a genial 55-year-old, spent 20 years as a Republican lawmaker, ending up as the leader of the Missouri Senate before term limits forced him to step down. In 2010, he became chief operating officer of one of Truman's hospitals, and in July he succeeded longtime Truman CEO John W. Bluford III. Now Mr. Shields, whose office décor includes a collection of elephant statues, must press the legislature's current Republican leaders to accept the Affordable Care Act's expansion of Medicaid, the federal-state insurance for low-income people. [Subscription Required]