Travel and visa restrictions imposed by the Trump administration threaten patient care at hundreds of hospitals that depend on medical residents recruited from overseas.

Foreign medical residents often serve as the frontline caregivers at busy safety-net hospitals in low-income communities. Normally the residents begin work on July 1. Orientation programs for some of them already started this week.

Now some of those hospitals are racing to prevent staffing shortages.

“If international medical graduates can’t start their medical residencies on time on July 1, the ramifications are so far-reaching that it is really unconscionable,” said Kimberly Pierce Burke, executive director of the Alliance of Independent Academic Medical Centers.

Senior residents leave hospitals in June and go on to start their careers, she noted. Hospitals rely on new residents to replenish their ranks. “If they don’t come on July 1, that leaves a hole in the patient care team,” Ms. Burke said. “Who’s going to pick up the slack?”