Washington — Sens. Kirsten Gillibrand, Kamala Harris and Amy Klobuchar — three of the Democratic members of Congress competing for the party's presidential nomination — are joining forces to call on the Trump administration to overhaul the policies in place for detaining and housing unaccompanied migrant children in U.S. custody.

In a letter to the director of the Office of Refugee Resettlement (ORR) on Tuesday, the trio of 2020 Democrats urged the Department of Health and Human Services (HHS) to ensure its facilities have proper oversight and to evaluate and change its policies regarding the care of unaccompanied minors, who are supposed to be transferred to HHS within three days of their apprehension by Border Patrol. Citing thousands of sexual abuse allegations reported by children in HHS custody, Harris, Gillibrand and Klobuchar said the changes are urgent.

"We cannot compromise on the safety and wellbeing of children facing extended lengths of stay in government custody," the senators wrote in their letter. ORR is the agency within HHS responsible for taking care of unaccompanied migrant children in U.S. custody.

Sens. Kamala Harris and Kirsten Gillibrand stand on a step ladder to observe youths incarcerated at a detention facility near Miami in Homestead, Florida, June 28, 2019. CARLO ALLEGRI / REUTERS

The senators — who visited the largest shelter for unaccompanied migrant children at Homestead, Florida, last week alongside other presidential candidates — noted that HHS has received the funding it requested for months.

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Congress last week approved a multi-billion-dollar funding package the Trump administration requested to deal with the months-long unprecedented surge of Central American families and unaccompanied minors heading towards the U.S.-Mexico border. A version of the legislation with stronger protections for migrant children in U.S. custody favored by Speaker Nancy Pelosi and progressives was derailed in the House after a group of moderates threatened to revolt.

"ORR should be prioritizing reunification of every child as soon as possible, but instead it has been responsible for policies that are forcing longer stays in government custody for children," Harris, Gillibrand and Klobuchar wrote in their letter. "You now have the funding you said you needed, and your office must ensure that the custody and processing of UACs is meeting the minimum standards required by domestic and international law."

Accusing some HHS shelters, which are typically operated by private contractors, of violating the Flores court settlement that governs the care of migrant children in U.S. custody, the three senators called on HHS to ensure that the companies it hires employ staff who go through proper vetting and that have adequate resources to take care of children.

Sens. Klobuchar and Kamala Harris talk before a Senate Judiciary Committee hearing on Thursday, Sept. 27, 2018 on Capitol Hill. Michael Reynolds / AP

Harris, Gillibrand and Klobuchar said these shelters need to have rigorous oversight to make sure they are abiding by the Flores agreement and other state requirements for the care of minors.

Although most of the shelters which house migrant children are subject to inspections by state child welfare authorities, some "temporary" ones — like the one in Homestead, Florida — are not required do undergo inspections since they are located on federal land.

This week, HHS opened a new "temporary influx shelter" in Carrizo Springs, Texas, on a site that was once used as a private dormitory "man camp" for oil field workers. HHS is also slated to start using an Army base in Oklahoma as one of these temporary shelters for unaccompanied migrant children in its custody.

The three senators said HHS should not open up any new of these "temporary influx" facilities.

"I urge you to ensure these 'temporary' shelters remain temporary and are beholden to stringent compliance requirements for state-licensing as they become operationalized," they wrote. "ORR must not establish or expand Influx Care Facilities that are not state-licensed or Flores-compliant without stringent compliance oversight."

Graham Kates contributed to this report.