Based on the American “constitution,” which internal and external stakeholders, in the policy-making process, possess “constitutional legitimacy” for their role in making public policy?

Discussion question: Based on the American “constitution,” which internal and external stakeholders, in the policy-making process, possess “constitutional legitimacy” for their role in making public policy? Do entities with explicit power have more influence than those entities with implied powers in making public policy? Should they? Why or why not?