The House Judiciary Committee on Tuesday announced that it plans to investigate the Department of Homeland Security's Migrant Protection Protocols (MPP), which has been dubbed the "Remain in Mexico" policy for forcing some asylum-seekers from Central America to wait in Mexico during their claims process.

In a letter, committee chairman Rep. Jerrold Nadler Jerrold (Jerry) Lewis NadlerHouse passes bill to protect pregnant workers House Democrats postpone vote on marijuana decriminalization bill Attacks against the police are organized and violent MORE (D-N.Y.) and immigration subcommittee members including Reps. Zoe Lofgren Zoe Ellen LofgrenDHS opens probe into allegations at Georgia ICE facility House passes legislation to boost election security research Hillicon Valley: Twitter flags Trump campaign tweet of Biden clip as manipulated media | Democrats demand in-person election security briefings resume | Proposed rules to protect power grid raise concerns MORE (D-Calif.) and Pramila Jayapal Pramila JayapalDHS opens probe into allegations at Georgia ICE facility Progressive Caucus co-chair: Whistleblower complaint raises questions about 'entire detention system' Buttigieg, former officials added to Biden's transition team MORE (D-Wash.) wrote to DHS acting Secretary Chad WolfChad WolfHillicon Valley: FBI chief says Russia is trying to interfere in election to undermine Biden | Treasury Dept. sanctions Iranian government-backed hackers Democrats slam DHS chief for defying subpoena for testimony on worldwide threats DHS IG won't investigate after watchdog said Wolf, Cuccinelli appointments violated law MORE, asserting that the protocols are illegal.

In a release announcing the move, Judiciary Democrats said they were announcing the investigation a year after the introduction of the Keep Families Together Act, which was proposed following public uproar over the Trump administration's "zero tolerance" policy that separated families at the border.

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"As we have previously written to you, MPP is inconsistent with the Department of Homeland Security’s (DHS) statutory authority, while exposing thousands of people to threats of murder, sexual violence, and kidnapping as they are forced to wait in extremely dangerous conditions before their asylum claims may be heard," the letter reads.

"As of today, there are 31 active travel advisories for Mexico, including 5 warnings in which the State Department explicitly advises Americans against travel. It is difficult to understand why this administration is sending children and families to areas where they will face certain harm," the members wrote.

The Remain in Mexico policy has been heavily contested by Democrats, who contend that it is illegal, and asylum officers who have argued in court that the policy abandons the U.S. tradition “of providing a safe haven to the persecuted and violates our international and domestic legal obligations.”

Nadler's move comes just hours after Fox News reported that the Trump administration has begun sending Mexican migrants from nonborder states on flights to central Mexico, a policy that reportedly began last month.

DHS officials told the news outlet that the agency could fly two flights a week totaling 250 migrants per week under the program.

Dozens of Senate Democrats wrote a letter to DHS last year opposing the MPP, writing at the time that the U.S. has "turned its back on its domestic and international legal obligations by forcing men, women, and children to await resolution of their U.S. asylum cases in parts of Mexico plagued by violence."

"It is imperative that the United States end this reckless course of action and reaffirm its commitment to the principles of due process on which this country was founded," they wrote in August.