Mike Waltz, who faced calls to resign over the Signal chat scandal, has sparked new scrutiny with his reported use of Gmail for official work.

During his first term, Trump's relationship with then-Chairman Gen. Mark Milley soured as Milley pushed back and took steps to try to prevent what he saw as an attempt to politicize the office. He would remind military service members that they took an oath to the Constitution, not to a president.

Democrats seemed to view Lt. Gen. Dan Caine as perhaps the best possible option, under the circumstances. Republicans embraced him.