“General Mattis has served the United States tirelessly, with admirable distinction. However, the unusual circumstances of his nomination raise serious questions about fundamental principles of our Constitutional order. Civilian control of the military is not something to be casually cast aside. So while I like and respect General Mattis a great deal, the House of Representatives would have to perform a full review, including hearings by the Armed Services Committee, if it were to consider overriding the statutory prohibition on recent military officers serving as the Secretary of Defense.

‎"I want to reiterate how much I admire General Mattis. I worked with him personally in the many positions he has held during his service. We have a close personal relationship, and I consider him an outstanding individual and officer. ‎I will be having close conversations with him in the coming days about how to ensure we maintain civilian control of the military."