US President Joe Biden has put Vice-President Kamala Harris responsible for controlling migration at the southern border following an enormous influx of latest arrivals.
Mr. Biden said he was giving her a “tough job” but that she was “the most qualified person to do it”.
The numbers of individuals arriving have grown since Mr. Biden took office.
They include many unaccompanied minors who are being held in immigration detention facilities.
Mr. Biden’s predecessor, Donald Trump, was widely criticized over his government’s treatment of young migrants at the US-Mexico border.
Since January, the Biden administration has reversed a policy of avoidance unaccompanied children, instead choosing to process them and place them with sponsoring families within the US.
But Mr. Biden’s critics say his policies have led to a surge in illegal migration.
In February, US Customs officials took quite 100,000 people into custody along the southern border, a 28% increase on the previous month.
Announcing Ms. Harris’s appointment as his immigration czar, Mr. Biden told reporters and officials at the White House: “She’s the foremost qualified person to try to to it, to steer our efforts with Mexico and therefore the Northern Triangle [Honduras, Guatemala, and El Salvador], and therefore the countries that are getting to need help in stemming the movement of numerous folks – stemming the migration to our southern border”.
Mr. Biden said Ms. Harris’s past work as California’s attorney general made her compatible with leading the trouble, adding: “When she speaks, she speaks on behalf of me.”
In response Ms. Harris said: “Needless to mention, the work won’t be easy. But it’s important to work.”
Many of these arriving at the border have fled poverty and violence in Central America.
In an interview on Wednesday, Ms. Harris said there was a requirement “to affect the root causes of what is happening within the Northern Triangle”.
“Dealing with what we’d like to try to around aid during a way that’s about developing those countries so that we also affect the explanation for why people are coming into our country,” she said.