The officials said there were more than 9,500 children in the custody of the Department of Health and Human Services and roughly 4,500 with US Customs and Border Protection.
That represents an increase just from earlier this week. The average length of stay for a child in HHS custody is 34 days, an official added.
Briefing reporters on Thursday, senior administration officials insisted it was former President Donald Trump’s policies that left them in the current predicament and said flows of migrants should be expected.
“Children presenting themselves at the border is not a national crisis,” said one of the officials, speaking on the condition of anonymity.
“January 20 was not suddenly the moment the border looked differently. Numbers increase and decrease all the time,” the official said.
“Adults are being turned back. Most families are being turned back. We can process and protect children coming to our borders seeking help as the law requires and our administration is doing that.”
Despite the administration’s efforts to downplay the current surge of migrants, CBP is on pace to encounter more individuals on the border than in the last 20 years, Homeland Security Secretary Alejandro Mayorkas said Tuesday.
He said the agency is coming across children as young as six and seven years old.
Mr Mayorkas’ television appearances this week, paired with briefings from officials, have been designed to show the administration is on top of the issue.
Mr Biden has drawn harsh recrimination from Republicans but also from some Democrats for his handling of it.
The administration officials said Thursday that most adult migrants and migrant families were being expelled.
But they acknowledged there were limitations on Mexico’s ability to take in migrants, particularly those with young children. And they repeated that the Biden administration would not expel unaccompanied minors.
“We’re dealing with the hand that we were dealt. The President inherited a mess,” an official said.
“We have a whole of government approach to clean up the mess.”
The administration’s focus now is on expanding capacity at its facilities and speeding up the processing of unaccompanied children that would allow them to move out of the government’s care more quickly, officials said on Thursday.
That includes altering COVID-19 protocols in ways that would increase the number of people allowed inside each facility, opening new facilities and paying for children’s flights or transportation to be reunited with family members or guardians.
Officials also emphasised they were working through diplomatic channels to try and address root causes of migration from Central America, which include violence, poverty and – this year – two devastating hurricanes.
But those efforts are longer term. For now, the administration said it was trying to quickly scale up capacity at new CBP facilities in Texas and Arizona to house the incoming migrants while also providing a basic level of comfort.
An official said the temporary processing facility operated by CBP in Donna, Texas — which houses most of the unaccompanied children arriving at the border — “has been designed to be able to provide the best care that is possible under the circumstances.”
The official said that included three meals a day, access to regular snacks, freedom of movement, telephone calls, showers and occasional outdoor recreational time.
“There is what I would say are folks doing the best they can to provide the care in a facility that is really not designed to be holding large numbers of children,” an official said.
Media requests to tour the Donna facility have been repeatedly denied as DHS cites COVID restrictions.
And while the White House said on Wednesday it would discuss releasing publicly photos taken by an administration delegation of the Donna facility earlier this month, it sounded unlikely a day later.
“There was a private briefing, an internal briefing from several weeks ago. We typically don’t provide those materials publicly, but we do want you to be able to, or a pool of media to be able to have your own visuals and get your own footage of these facilities,” White House press secretary Jen Psaki said.