LBJ ranks near the bottom of my list, but to me, nobody, not even TRIPOTUS X42 himself, was as incompetent and clueless as Jimmy "I never met a dictator I didn't coddle" Carter.
I42 is a close second though.
5.56mm
Carter is in the runner up category. The one election I was saddest about bar none in my memory, was when Carter beat Ford. I used the F word many times that election night. My lack of confidence in Carter's ersatz act, and lack of competence and experience and judgment, proved amply justified by events, and that of course was unfortunate. I wished I had been proven wrong. I wasn't.