With the latest Republican health care overhaul teetering near collapse, one group in particular is watching with heightened anxiety.

The debate in Congress is personal for many of those who gained coverage through Medicaid in the 31 states that expanded the program under former President Barack Obama's Affordable Care Act.

Alan Purser, who lives in eastern Arkansas, credits expanded Medicaid with saving his life, after a routine doctor's visit ended with him being hospitalized and treated for multiple blood clots in both lungs. The 60-year-old diabetic said he would not be able to afford his...