Stephen Miller has been appointed as the new White House chief of staff, succeeding Susie Wiles, President Donald Trump announced Monday. Miller, described by Trump as one of his "most trusted advisors," will assume the role on Monday.

Trump expressed his gratitude to Wiles for her service, stating she "has done a great job." Wiles, who has served as chief of staff for 21 months, making her the longest-serving in that capacity across Trump's terms, will transition to work within Trump's political operation. "Today is my last day as White House Chief of Staff," Wiles said in a statement. "Serving President Trump in the White House has been the honor of a lifetime. I’m so proud to have been a part of what we’ve accomplished together from securing our border and cutting taxes to strengthening our economy and putting America First."

She added, "More than anything, I’m grateful for the extraordinary people I’ve had the privilege of working alongside. While my role may be changing, my commitment to the President and the mission never will."

Miller's appointment marks a significant shift in the White House's senior staffing.