Rodney served six terms as State Representative, from the 1797 session through the 1802 session. There he became one of the leaders of the Jeffersonian party, now known as the Democratic-Republican Party. Encouraged by Jefferson to compete for the U.S. House against the staunch Federalist James A. Bayard, Rodney ran and won a lively campaign by fifteen votes. While in the U.S. House, he was a member of the Committee on Ways and Means, and established a national reputation as one of the managers appointed in January 1804 to prepare the articles of impeachment against John Pickering, judge of the United States District Court for New Hampshire. Pickering was charged with conduct unbecoming a judge, and his acquittal was viewed as strengthening the independence of the judiciary. In December of the same year, Rodney led another such case against Samuel Chase, Associate Justice of the Supreme Court of the United States.