A group of Senate Democrats want the private prison industry to explain whether it is complying with federal standards for housing at ICE immigration detention centers.

Led by Massachusetts Democratic Sen. Elizabeth Warren, the senators have written to CoreCivic and GEO group about their housing practices following reports from the inspector general at the Homeland Security Department.

“These reports and the results of the OIG investigations indicate that the perverse profit incentive at the core of the private prison business model has resulted in GEO Group and CoreCivic boosting profits by cutting costs on expenditures including food, health care, and sufficient pay and training for guards and prison staff,” the senators wrote.

The senators want answers by the end of the month.

The signatories on Warren’s letters included a bunch of other potential 2020 presidential hopefuls such as Cory Booker of New Jersey, Kirsten Gillibrand of New York, Kamala Harris of California, Jeff Merkley of Oregon and Bernie Sanders of Vermont.

Among the requests are for the prison operators to turn over any waivers that may have been granted by Immigration and Customs Enforcement for noncompliance with relevant standards.

“In their review, OIG found that detainees in immigration detention facilities do not have access to basic necessities or prompt and adequate medical care,” the senators wrote.

Specifically, they cite a report about disturbing findings on the frequency of suicide attempts at a GEO Group-operated ICE facility in Adelanto, California.

“The report found that in 15 out of approximately 20 cells examined inspectors saw nooses fashioned from twisted bedsheets hanging from vents,” they said. “A detainee quoted in the report explained that detainees use braided bedsheets to attempt to commit suicide.”