What if they appointed some staffers to keep roleplaying with him that he's still president a la Truman Show.

They fix some fake interviews, play dress up and all, give fake assignments, take him for a walk around the WH lawn where fake journos and cameramen await, etc.

Then he starts noticing weird things and asks a staffer "hey hold on a minute... Why's Kamala sleeping in the bigger bed now and why am I on the couch?"

Staffer starts sweating and signals to control room to trigger a distraction to break his train of thought