Some of these community health centers may have to cut medical and administrative staff or reduce services. Some could eventually close. The result, their advocates warn, may be added pressure on already crowded hospital emergency rooms.

“This is the worst time in all the years I have been working in health care,” said Jim Mangia, president and CEO of St. John’s Community Health, a network of 28 clinics that serves more than 144,000 patients in Los Angeles, Riverside, and San Bernardino counties in California. “We are facing federal cuts and extreme state cuts that will impact services.”

St. John’s and other federally qualified health centers offer primary care and a wide range of other services free of charge or on a sliding fee scale. Nationwide, they see nearly 34 million patients in the country’s most underserved areas.