The 1796 election was the first US Presidential election involving more than one candidate. With incumbent President George Washington having refused a third term in office, incumbent Vice-President John Adams of Massachusetts became a candidate for the presidency on the Federalist Party ticket with former Governor Thomas Pinckney of South Carolina as the next most popular Federalist. Their opponents were former Secretary of State Thomas Jefferson of Virginia along with Senator Aaron Burr of New York on the Democratic-Republican ticket. At this point, each man from any party ran alone, as the formal position of "running mate" had not yet been established.
While Adams won the presidency, his preferred choice for the Vice Presidency, Pickney, failed to pick up enough electoral votes to be elected. Instead, the office went to Jefferson. This is the only occurrence in US history of the president and vice president being from different parties and provide impetus for the 12th Amendment.
What if Adam's electors are able to better coordinate and Pickney becomes the Second Vice President of the United States?