Final answer:
Congress must approve the federal budget due to its constitutional power of the purse, serving as a check and balance on the president. The president proposes a budget and can veto Congress's version.
Step-by-step explanation:
The Congress must approve the budget, including the president's proposed annual budget for federal expenditures, because it has the constitutional power of the purse.
This means Congress has the ability to control government spending and is thereby a fundamental check and balance on presidential power.
The House of Representatives initiates all taxing and spending bills, and the Senate can propose changes, with both houses needing to agree before a budget is presented to the president.
If the president is not in agreement with the proposed budget, he has the option to veto it, requiring Congress to either revise the bill or attempt to override the veto with a two-thirds majority vote in both houses.
Historically, the budget process underwent significant change following World War I, leading to the creation of the Budget and Accounting Act of 1921.
This gave the president the role of chief budget agenda setter and led to the establishment of a budget staff, which later became the Office of Management and Budget.
Despite these capabilities, Congress retains the final authority to determine how federal revenue will be spent, which is a powerful tool for shaping policy, including foreign policy and national security measures subject to Congress’s oversight and approval.