Most presidents remained associated with a certain political party from early in their careers until the ends of their lives, though a few changed their affiliations. Before he was elected to the vice presidency in 1840, John Tyler switched his political allegiance from the Jackson Democrats to the newly formed Whig Party. Once Tyler succeeded to the presidency after President William Henry Harrison died in office, he abandoned many Whig principles, lost the support of his Whig cabinet, and was ejected by the party. In the 1930s and 1940s, Ronald Reagan was a Democrat; however, he gradually adopted a more conservative political ideology and officially changed his political affiliation to Republican in 1962. Reagan served as Republican governor of California from 1967 to 1975 and as the Republican president for two terms, from 1981 to 1989.

Three presidents changed their party affiliation after their presidency: Martin Van Buren, a Democrat, became a candidate for the Free Soil Party; Millard Fillmore, a Whig, became a candidate for the American, or Know-Nothing, Party; and Theodore Roosevelt, a Republican, founded the Progressive—or Bull Moose—Party.