WASHINGTON — A group of 18 Republican congressman are urging the Trump administration to defend private prisons against lawsuits alleging immigrant detainees are forced to work for a wage of $1 a day.

The members say that Congress in 1978 had explicitly set the daily reimbursement rate for voluntary work by detainees in U.S. Immigration and Customs Enforcement facilities, and that the same rate should apply in government-contracted private prisons.

“Alien detainees should not be able to use immigration detention as a means of obtaining stable employment that will encourage them to pursue frivolous claims to remain in the country and in detention for as long as possible,” the lawmakers wrote in a letter to Attorney General Jeff Sessions, Labor Secretary Alexander Acosta, and acting ICE director Thomas Homan.

In the March 7 letter, first reported byThe Daily Beast, the congressmen argue that the detainees are not employees of private prisons so should not be able to file lawsuits seeking to be paid for their work.

“It is our expectation that you will soon get involved in this litigation and take the position that these lawsuits lack legal merit and should be dismissed,” they said.

The Department of Justice did not immediately respond to a request for comment.

At least five lawsuits have been filed against private prisons, including The GEO Group and CoreCivic, over detainee pay and other issues. The lawsuits allege that the companies use voluntary work programs to violate state minimum wage laws, the Trafficking Victims Protection Act, unjust enrichment and other labor statutes.

The state of Washington sued GEO last year for violating its minimum wage of $11 an hour and sought to force the company to give up profits made through detainee labor. The state argued that the wage floor should apply because GEO is a private company detaining people on civil, not criminal, charges.

In seeking to dismiss the case, the company asserted that the federal rate for work performed by detainees trumps that state’s minimum wage law.

“This is detention. It’s not a competitive work environment,” GEO attorney Joan Melltolda federal judge last November.

Inmates in Colorado and California have also sued the Boca Raton-based company, alleging that they were forced to work for $1 per day to pay for basic necessities like food, water and hygiene products. Detainees performed janitorial work such as scrubbing floors and cleaning windows, as well as clerical work, washing laundry, even cutting hair. Detainees who objected were punished by “disciplinary segregation or solitary confinement” or referred for criminal prosecution, one suit alleged.

The company has repeatedly denied that detainees are forced to work against their will.

The congressmen’s letter, filed with a U.S. District Court in California by GEO this week, asserted that paying working detainees more than the $1 a day required by federal law would “provide an unnecessary windfall to the detainees, and drain the federal government of limited taxpayer resources.”

They assert that immigrant advocates, including officials in so-called sanctuary cities, have filed the “nuisance lawsuits” to raise the overall costs of immigration detention to discourage its use and diminish the overall level of immigration enforcement.

The letter was signed by Republicans Steve King of Iowa; Lamar Smith, John Ratcliffe, Louie Gohmert and Brian Babin of Texas; Mike Rogers of Alabama; Paul Gosar and Andy Biggs of Arizona; Matt Gaetz and John Rutherford of Florida; Dana Rohrabacher, Paul Cook and Duncan Hunter of California; Scott Taylor of Virginia; and Earl L. “Buddy” Carter, Jody Hice and Barry Loudermilk of Georgia; and Bob Gibbs of Ohio.