The Justice Department  told the Associated Press  it's "worked tirelessly" since Friday to try to reunite migrant children with their families.

But the American Civil Liberties Union says it appears the federal government won't hit the court-ordered July 10 deadline.

That's the date  a federal judge said all children under the age of 5 had to be reunited with their families.  Over the weekend, the ACLU  confirmed to CNN  it received a list of almost 100 kids under 5 who'd been separated from their families at the U.S.-Mexico border.

On Sunday, it said it didn't believe  that "even half"  would be reunited with their parents by the deadline.

The Trump administration has  already asked  for more time.

On Friday, the judge refused to issue a blanket extension, but he's scheduled to consider  possible exceptions  on a case-by-case basis Monday.

Last week, Health and Human Services Secretary Alex Azar estimated  fewer than 3,000  migrant kids were in government custody.   All children must be reunited with their families by July 26.  Additional reporting from  Newsy affiliate CNN .