Final answer:
Congress has the power to override a presidential veto with a two-thirds majority vote in both the House and the Senate. However, only about four percent of all vetoes have been successfully overridden.
Step-by-step explanation:
Congress has the power to override a presidential veto, but it requires a two-thirds majority vote in both the House and the Senate. Only about four percent of all vetoes have been successfully overridden, which means that Congress doesn't override a presidential veto half of the time.