Final answer:
Congress has the power to override presidential vetoes with a two-thirds majority vote in both chambers, but this has only happened approximately four percent of the time, reflecting the strong position of the president in legislative matters.
Step-by-step explanation:
The ability of Congress to override presidential vetoes has been exercised throughout United States history, but it is a relatively rare occurrence. When a president vetoes a bill, the Constitution gives Congress the power to override that veto with a two-thirds majority vote in both the House of Representatives and the Senate. However, only approximately four percent of presidential vetoes have been overridden, showing the significant influence the president holds with this legislative tool. The override of a veto is usually a challenging endeavor due to the high vote threshold required and the political dynamics involved.
The threat of a veto can influence how legislation is shaped, as members of Congress are often motivated to avoid the veto by making the bill more acceptable to the president. This illustrates the complex system of checks and balances between the legislative and executive branches. Political realities, such as whether the government is divided or unified under one party, also play a key role in the likelihood of a successful veto override.