Aaron Burr and Thomas Jefferson were from different political parties. Even so, Burr was Jefferson’s vice president. This is because presidents and their vice presidents did not run as a ticket in those days. The Constitution had set things up so that the person who got the most electoral votes became president and the person who got the second most became vice president. Once the US started to develop true political parties, this essentially meant that the president and vice president would always be from different parties. Because of the 1800 election, the Twelfth Amendment to the Constitution was passed and ratified, creating a new system where electors voted for president and vice president separately.