The election of 1800 marked the decline of the Federalist party and the emergence of the Democratic-Republican party.
The Federalist Party emerged out of the Constitutional Convention and were led by John Adams and Alexander Hamilton. The Federalist Party believed in a centralized federal government and a government run by a smaller, elite group of men. The party had control of the government under the first two presidents: Washington and Adams. The party would not have another president in office and completely disappeared as a party following the War of 1812.
The Democratic-Republican Party emerged as a reaction to the Adams presidency. Specifically, under the leadership of Thomas Jefferson, the party was created to express concern over the Alien and Sedition Acts. Democratic-Republicans picked up the ideas of the Anti-Federalists from the Constitutional Convention. They believed in more state power and a reduction of federal power. The group led the government officially until the mid-1820's. However, the philosophy of the party began to move more toward the middle following the War of 1812 as the US entered the "Era of Good Feelings".