US President Donald Trump announced Friday that a senior department official, Chad Wolf, would become the nation's new acting homeland security chief, a role at the center of his crackdown on undocumented immigration.

Asked to confirm rumors that Wolf, a department undersecretary, would assume the role, Trump told reporters: "Well he's right now acting and we'll see what happens. We have great people in there."

Trump announced the resignation of his current acting secretary, Kevin McAleenan, three weeks ago, marking the latest departure in a long list of top officials to leave his administration.

"As the president has said, Kevin McAleenan has done a tremendous job. He'll be leaving after Veterans Day and after he departs, Chad Wolf will serve as acting secretary in the interim," White House spokesman Hogan Gidley said.

McAleenan served in the role for six months, replacing Kirstjen Nielsen, who sat at the helm of the powerful agency for 18 months.