The American Civil Liberties Union said it appears the Trump administration will miss a court-ordered deadline to reunite young children who were separated at the border with their parents in more than half of the cases. The ACLU said late Sunday the administration provided it with a list of 102 children under 5 years old and that "appears likely that less than half will be reunited" by Tuesday's deadline.

The Justice Department asked U.S. District Judge Dana Sabraw for more time last week but the judge on Friday did not grant a blanket extension, saying only that he would consider certain exceptions. He told the two sides to discuss possible exceptions and report to him Monday. The Justice Department was working through the weekend on a path toward unification and was preparing a progress report for the court.

An administration official said in a statement to CBS News that the administration has worked "tirelessly since Friday's status conference toward the shared goal of promptly reunifying families while ensuring the safety of the children."

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"The results of that work have been highly encouraging, and the Department of Justice is eager to present its progress to the court on Monday and to chart a path forward to safely reunifying other families expeditiously," the official added.

According to an administration official, the DOJ now believes the government is on track to reunify almost all of the those currently eligible by tomorrow, CBS News' Paula Reid reports. There will be some outstanding cases including children whose parents are wanted for felonies in their homeland.

Children were increasingly separated from their parents after Attorney General Jeff Sessions announced in May that a zero-tolerance policy on illegally entering the country was in full effect. While parents were criminally prosecuted, children were placed in custody of the Health and Human Services Department.

Trump reversed course on June 20 amid an international outcry and said families should remain together.

On June 26, Sabraw set deadlines of Tuesday to reunite children under 5 with their families and July 26 for older children. Sabraw, who was appointed by President George W. Bush, wrote that the "situation has reached a crisis level" and that the "chaotic circumstances" were of the government's own making.

Health and Human Services Secretary Alex Azar said Thursday there were "under 3,000" children separated from their parents. Previously, he said 2,047.

"It's extremely disappointing that the Trump administration looks like it will fail to reunite even half the children under 5 with their parent," said ACLU attorney Lee Gelernt. "These kids have already suffered so much because of this policy, and every extra day apart just adds to that pain."

The ACLU sued in March on behalf of a Congolese woman who was separated from her daughter for five months after seeking asylum at a San Diego border crossing and a Brazilian asylum-seeker who was separated from her son after an arrest for illegal entry in August near the Texas-New Mexico border.