Roberta Jacobson, the former ambassador to Mexico, was chosen as President Biden's border czar amid pressure from lawmakers to address what some are calling a "crisis" at the southern border.
"Consistent with her commitment to serve in the administration's first 100 days, Ambassador Jacobson will retire from her role as Coordinator at the end of this month," National Security Advisor Jake Sullivan said in a statement.
Sullivan praised Jacobson's work in shaping the relationship between the U.S. and Mexico and renewed efforts to cooperate with Northern Triangle nations of El Salvador, Guatemala and Honduras, home to many migrant children making the dangerous passage to the U.S.
More than 16,000 unaccompanied migrant children are in the care of the Department of Health and Human Services (HHS) and another 4,000 in the care of Customs and Border Protection, according to official figures. CBP announced on Thursday that there have been 172,000 migrant encounters in March, of which nearly 19,000 involved unaccompanied children.
The administration has blamed Trump's dismantling of asylum systems for the "challenge" it faces at the border while Republicans have cited Biden's immigration policies and messaging.
In a statement to The New York Times, Jacobson praised Biden's effort to repair and recast the nation's immigration system after four years under former President Trump.
"They continue to drive toward the architecture that the president has laid out: an immigration system that is humane, orderly and safe," she said in a brief interview. "I leave optimistically. The policy direction is so clearly right for our country."
She noted that her appointment was always intended to last 100 days, which will expire at the end of April.
Biden has tapped Vice President Kamala Harris to lead diplomatic efforts to work with Mexico and Central American countries on improving conditions in the region. Harris has been sharply criticized for failing to visit the border.
Jacobson told the Times she was confident the administration would make progress in slowing the flow of migrants.
"They know it is something that can’t happen overnight," she said. But she added that officials in the other countries were motivated to find solutions, as well.
"Diplomacy is a conversation," she said. "It’s not a monologue."