Final answer:
A veto is the power to reject a bill, which can still become law if both the House and Senate pass it again with a two-thirds majority to override the veto. The threat of a veto can influence legislative changes, and a "pocket veto" occurs if the president doesn't sign a bill within ten days and Congress adjourns.
Step-by-step explanation:
A veto is the power of the president or a governor to reject a bill passed by the legislature, effectively preventing it from becoming law. However, even after a veto, a bill can still become law if it overcomes the veto through a supermajority vote. In the United States, if the president vetoes a bill, Congress can override this veto by passing the bill again with a two-thirds majority in both the House of Representatives and the Senate. Similarly, at the state level, a governor's veto can be overridden by the state legislature with a supermajority vote, though the specific majority required may vary by state.
The threat of a veto can be a powerful political tool. It can influence legislators to modify a bill to make it more acceptable to the president or governor. In some instances, the possibility of a veto might lead to concessions or encourage negotiations that alter the bill's provisions before it passes. Conversely, a bill that is very popular or considered urgent might compel the president to sign it to avoid the potential political fallout from a veto.
There is also a situation known as the "pocket veto", where if Congress adjourns within ten days of sending a bill to the president, and the president does not sign it, the bill does not become law. Unlike the regular veto, a pocket veto cannot be overridden.