Was Jefferson a Democrat?
Many Democrats like to claim that their party has been in existence since 1792, when Thomas Jefferson founded the "People's Party" in opposition to the conservative Federalist Party founded by Alexander Hamilton. If this is true then Jefferson, Madison, Monroe, and John Quincy Adams were all members of the same party as Bill Clinton. Unfortunately, to call the former men Democrats is disingenuous, as the modern Democratic Party was formed by a man who felt betrayed by the Democratic-Republican Party establishment: Andrew Jackson.
Jackson formed the Democratic Party after the "Corrupt Bargain" of 1824, in which none of the four presidential candidates (all Democratic-Republicans) won the necessary votes in the electoral college for victory. The election then went to the House of Representatives, where Speaker of the House Henry Clay (himself an underdog presidential candidate) used his influence to throw the election to John Quincy Adams, who then coincidentily selected Clay to be his Secretary of State afterwards. Jackson, who had won 40% of the popular vote versus Adam's 30%, was infuriated. Four years later, he and his newly founded Democratic Party cruised to victory in a landslide.
Democrats acknowledge Andrew Jackson's important place in party history, and sure enough, fundraisers are known as "Jefferson-Jackson Day Dinners."