If David Lopez is feeling the heat, he doesn't let on. As CEO of one of the nation's largest public health systems and leader of a multibillion-dollar project with the potential to change the way Texans get medical care, Lopez is under new scrutiny from his peers. The Texas Health and Human Services Commission tapped Lopez to oversee the creation of a regional plan, part of a complicated project known as the Medicaid 1115 waiver, intended to determine who gets paid—and how much—for providing charity care. Hospitals that historically have received the most federal money for treating people without health insurance are not guaranteed to do so under the new rules.