Wagner is the acting assistant secretary for the Administration for Children and Families, which is part of the Department of Health and Human Services.
Wagner's statement has attracted more attention amid reports that immigrant children are being separated from their parents at the US border.
Wagner said the Department of Homeland Security referred more than 40,000 immigrant children to the ORR during the 2017 fiscal year.
Between October and December 2017, Wagner told the subcommittee, the ORR reached out to 7,635 unaccompanied children to check on them.
But the ORR "was unable to determine with certainty the whereabouts of 1,475 children," Wagner testified.
But if the ORR were to be legally responsible for the well-being of unaccompanied immigrant children , it would need a significant increase in resources.
"You have an option to go to a port of entry and not illegally cross into our country. »