Does worst mean:

• least able to achieve their stated agenda, ie worst at their job. (Trump)
• worst vision for America, ie most evil (Reagan)
• worst overall impact to America, ie one you’d kill with a time machine (Bush Jr, but Trump might catch up in term 2)
• Worst for the word, ie the one I’d kill with a time machine (Washington)

Although I’m not American and don’t know your history that well.