DES MOINES, Iowa — Iowa is having trouble hiring enough registered nurses to treat prison inmates, so it’s turning to workers with fewer credentials to fill a gap created in part by more competitive benefits in the private sector.

Some unions representing Iowa nurses argue the staffing shortage will only worsen as the effects of recent changes to the state’s collective bargaining law begin to set in, though state officials say it’s too early to know its impact on hiring.

The Iowa Department of Corrections says a shortage of registered nurses at some clinics within its nine prisons has led the agency to seek more licensed practical nurses. Known as LPNs, they need less health care education and are paid less. They can do similar tasks as registered nurses, but they carry restrictions in their interactions with patients and require more oversight.

Kathy Weiss, administrator of nursing for corrections, said it’s difficult to compete with nearby hospital jobs that offer signing and retention bonuses and student loan repayment options. The department’s roughly $377 million budget was cut by about $8 million over the past year as lawmakers grappled with general fund shortfalls. A special session may be called soon to plug another shortfall.

“It’s hard to recruit nurses … we can’t offer some of the packages that the hospitals do,” Weiss said.

There were 24 nursing vacancies at Iowa prisons this summer, according to agency documentation distributed in July. Of those, 20 slots were for registered nurses and four slots were for licensed practical nurses. Corrections data for August indicates there are now 15 openings for registered nurses and six openings for LPNs. A total of 135 nurses are working for Iowa prisons.

More than half of the vacancies listed in the agency documentation were at the Iowa Medical and Classification Center in Coralville. Weiss said staffing issues are prevalent in urban areas that have additional job options for registered nurses.

Cathy Glasson, president of Service Employees International Union Local 199, which represents more than 3,000 public registered nurses in Iowa, said nursing shortages won’t improve under Iowa’s new collective bargaining law. The law prevents most public employees from negotiating health insurance and other working conditions.

The GOP-led Legislature approved the changes in February and then-Gov. Terry Branstad quickly signed the bill into law, saying it would give local governments more flexibility over budgets. Democrats and unions warned it would lead to job shortages as teachers, nurses and correctional officers moved out of state for better employment opportunities.

There is limited data to measure impacts of the collective bargaining changes in Iowa. The legislation is similar to a law passed in Wisconsin in 2011. Federal data shows union membership for public and private workers in Wisconsin decreased from 355,000 in 2010 to 219,000 in 2016, a nearly 40 percent drop. The state’s education agency has also recently eased some hiring and licensing rules to address a teacher shortage in the state, though new national studies show a growing teacher shortage in other states, too.

Glasson said Wisconsin is a cautionary tale for Iowa.

“This is a story that we’ve read before and will obviously impact nurses, teachers and other public employees in the state of Iowa,” said Glasson, a registered nurse who is seeking the Democratic nomination for governor next year.

Danny Homan, president of the American Federation of State, County and Municipal Employees Iowa Council 61, said in an email his organization has observed an exodus of state employees, particularly with seniority, “because the benefits and work environment can’t compete with the private sector.” AFSCME represents 95 registered nurses and 12 LPNs at the prisons, and is the state’s largest public employees union.

Corrections spokesman Michael Savala said in an email the collective bargaining changes are new “and the DOC will be seeing what impact they might have.”

Corrections officials noted a nationwide nursing shortage has existed for years, as the population ages and requires more medical care.

There are more than 46,000 registered nurses in Iowa, according the Iowa Board of Nursing. And while data shows more people in Iowa are seeking educational opportunities to enter nursing, some may not stay in the state. The latest federal and state data shows the median wage earned by Iowa registered nurses is $25.92 an hour, compared to a median wage nationally of $32.45 an hour.

“What are their opportunities in Iowa? What is the pay? What are the hours?” asked Kathy Weinberg, executive director for the Iowa Board of Nursing. “There’s lots of variables.”

Weiss, the head of nursing for corrections, said the hiring moves will not impact health care services at the prisons, adding, “We’re still going to provide the same nursing care that we have had in the past.”

Lynn Boes, legal counsel for the Iowa Nurses Association, said the key will be hiring experienced LPNs.

“The more seasoned people you have, the more it will inform their nursing judgment,” she said.