Since both New Yorkers belonged to opposing political parties, Burr a Republican and Hamilton a Federalist, they developed an adversarial political relationship, according to the Library of Congress. The two were at odds in the controversial presidential election of 1800, when Hamilton helped secure Thomas Jefferson's victory at the expense of Burr, who became vice president. (In those days, the runner-up in presidential elections became vice president.) Hamilton wrote then that Burr's "public principles have no other spring or aim than his own aggrandizement," according to David Stewart, writing for the Constitution Daily blog.
Over the years Hamilton had also called Burr "embryo-Caesar" and remarked that he was "unprincipled both as a public and private man." In 1804, Burr lost an election for New York governor and blamed Hamilton for more personal insults.