Amending the Constitution was meant to be hard, which is why it's happened only twice since 1968. Any president looking at this record of futility would find plenty of reasons not to try. One is that he's highly unlikely to succeed, and presidents don't look for opportunities to lose. Getting a constitutional amendment requires mobilizing a strong national consensus on a particular issue. It requires persuading each house of Congress to muster a two-thirds vote in favor of a specific proposal. And it requires ratification by three-quarters of the states. Even if the amendment had a plausible chance of passage, writes Steve Chapman, it would probably take longer to achieve than a president's tenure in office.