The fate of hundreds of undocumented children taken from parents remains unclear a day after President Donald Trump moved to roll back his policy.
He ordered on Wednesday that the children be held with their parents while they are detained on charges of crossing the border illegally.
But under US law, migrant children cannot be detained more than 20 days by immigration officials.
Melania Trump has visited a child immigration detention centre in Texas.
US officials have expressed mixed messages about what happens next to at least 2,300 children taken from their parents since 5 May after entering the country without documentation.
While the adults are held in custody pending court appearances, the children are being sent to holding cells, converted warehouses and desert tents under the “zero tolerance” policy introduced in April.
If the administration wants to detain migrant families together indefinitely while their cases churn through the legal system, it will need Congress or the courts to change the existing rules.