The U.S. Constitution specifies that the president shall be an elected representative of the people, and afforded only certain powers while occupying that office. This concept is called
direct democracy
judicial review
republicanism
rule of law
I think it is rule of law or republicanism. It can't be judicial review because the question does not mention anything about the judicial branch. It can;t be direct democracy either because America does not have direct democracy. I'm pretty sure it's Rule of law though. I hope this helped!