In 1820 Buchanan ran for the U. S. House of Representatives and won, though his Federalist Party was waning. During his tenure in Congress, he became a supporter of Andrew Jackson and an avid defender of states' rights. After the 1824 presidential election, he helped organize Jackson's followers into the Democratic Party, and he became a prominent Pennsylvania Democrat. In Washington, he was personally close with many southern Congressmen, and viewed some New England Congressmen as dangerous radicals. He was appointed to the Committee of Agriculture in his first year, and he eventually became Chairman of the U.S. House Committee on the Judiciary. He declined re-nomination to a sixth term, and briefly returned to private life.