The need for amending the procedures set forth in the Constitution for electing a president and vice president were necessary because of the ambiguity in Article II, Section I. In just over a decade after the Constitution was ratified, there had been two presidential elections--the election of 1796 and the election of 1800--that had confusing outcomes.
In 1796, the president and vice president ended up coming from different parties. Then in 1800, there was a tie for president, and Congress almost didn't agree on a winner. It didn't take long before Congress saw the need to clarify the procedures with the 12th Amendment, and over the next 200 years, the need for a few more amendments dealing with the presidency became evident
