The presidency is now thought of as a representative institution. I argue that the idea of presidential representation, the claim that presidents represent the whole nation, influenced the political development of the institutional presidency. Specifically, I show that the idea was the assumption behind creating a national budget system in the United States. While the challenge of World War I debt prompted Congress to pass the Budget and Accounting Act of 1921, the law’s design owes much to reformers’ arguments that the president lacked institutional tools to fulfill his representative role. Congress institutionalized presidential representation in budgeting by including two key components: a formal license for presidential agenda setting in the budget process and an enhanced executive organizational capacity with the Bureau of the Budget. However, the law also revealed the problems raised by attempting to provide the “proper organs” for presidential representation, which push against the written constitutional frame.