The only Federalist President, John Adams, was defeated in the election of 1800 by

The only Federalist President, John Adams, was defeated in the election of 1800 by Thomas Jefferson

In what is sometimes referred to as the "Revolution of 1800", Vice President Thomas Jefferson of the Democratic-Republican Party defeated incumbent President John Adams of the Federalist Party. The election was a realigning election that ushered in a generation of Democratic-Republican rule.