President Donald Trump has said Kevin McAleenan is out as the acting secretary of the Department of Homeland Security.
Mr Trump said he will be announcing a new acting secretary in the next week.
The president said on Twitter that Mr McAleenan has done an outstanding job and border crossings are down.
But Mr Trump said Mr McAleenan wants to “spend more time with his family and go to the private sector”.
The president said there are “many wonderful candidates” to fill the position.