Updated

California lawmakers are on the verge of passing a bill that would significantly scale back solitary confinement in prisons, jails and private immigration detention centers. 

Under the California Mandela Act, AB 2632, solitary confinement would be limited to no more than 15 consecutive days and no more than 45 days total in a 180-day period. 

Solitary Confinement Cell

An immigrant detainee makes a call from his 'segregation cell' at the Adelanto Detention Facility in Adelanto, California. (John Moore/Getty Images)

Meanwhile, solitary confinement would be eliminated entirely for pregnant women, people with certain disabilities and inmates under 25 or over 65. 

Sources tell Fox News that the current vote in the Senate for AB2632 is 20-10. It needs 21 to pass. 

Assemblyman Chris Holden, D-Pasadena, who introduced the bill in February, previously called solitary confinement "cruel and a racial justice issue that does nothing for the rehabilitation of a person." 

"Not only is it deemed as cruel and unusual punishment by the United Nations, but it deeply damages the psyche of a person," Holden said, according to the Sacramento Bee

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Sen. Brian Dahle, R-Bieber, who is running for governor to replace Gov. Gavin Newsom, has criticized the bill, arguing that it would allow gang leaders to be free among the general population. 

"Basically, we have no tools to keep other prisoners safe from people who are very violent in prison," Dahle said. "If you’re in prison here in California, and you’re violent against other prisoners, or you’re using your ability to be a gang leader, this is very egregious towards other prisoners." 

Holden rejected those claims as false, saying a "facility may choose to hold someone in an individual cell, if and when appropriate, after the 15 day limit is reached." 

"The bill does require individuals have access to out of cell rehabilitation programming and social interaction after 15 days," Holden said in a statement provided to Fox News. "There are ways to keep individuals safe and away from others if necessary, without resorting to complete isolation and 23 hours lockdowns." 

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He added: "The Mandela Act will focus on solutions that actually contribute to true rehabilitation and reduce the harm of solitary confinement."