Democratic presidential hopeful Bernie Sanders wants private companies out of the business of running prisons and immigration detention centers. The Vermont senator introduced legislation on Thursday to end for-profit prisons. 

The independent Vermont senator announced the "Justice Is Not For Sale Act," which would also end the practice of detaining immigrants and asylum seekers, according to a press release.

The bill, which he will sponsor alongside fellow Democrat Raúl Grijalva, a congressman from Arizona, would prompt the federal government to stop contracting private companies to oversee prison within two years of the bill's passing and increase oversight meant to ban companies from overcharging inmates and families for services such as phone calls. It would also reinstate the federal parole system abolished in 1984.

"We cannot fix our criminal justice system if corporations are allowed to profit from mass incarceration," Sanders said. "Keeping human beings in jail for long periods of time must no longer be an acceptable business model in America. We have got to end the private prison racket in America. Our focus should be on treating people with dignity and ensuring they have the resources they need to get back on their feet when they get out." 

Some observers see the move as a reaction to criticism Sanders faced for declining to address issues such as immigration and criminal justice reform on the campaign trail, reports Politico.

The White House hopeful aims to broaden his appeal among African-American and Latino voters, both considered key constituencies in the Democratic nominating process.

His main rival, Hillary Clinton, for her part, has voiced concerns about privately run prisons on the campaign trail. But the Democratic front-runner has received thousands of dollars in campaign contributions through lobbyists linked to two major private prison companies, an Intercept investigation found.

As first lady, the wife of then-President Bill Clinton also championed efforts to get tough on crime.

"We need more police, we need more and tougher prison sentences for repeat offenders," Clinton said in 1994.

"The 'three strikes and you're out' for violent offenders has to be part of the plan. We need more prisons to keep violent offenders for as long as it takes to keep them off the streets," she added.

In the United States, about 18 corporations currently guard some 10,000 prisoners in 27 states, according to the Canadian Centre for Research on Globalization.