Article continues below advertisementDonald Trump is not helping to dispel the rumors about his mental fitness. In an embarrassing flub aboard Air Force One on Monday, February 16, the 79-year-old president forgot he already backed a candidate to replace former Rep. Marjorie Taylor Greene's seat in the House. When asked about his upcoming visit to Greene's former district, Rome, Georgia, on Thursday, Trump appeared to have no memory that he endorsed Republican congressional hopeful Clay Fuller nearly two weeks ago.