 Thus, the balance of power in the Senate changed from 51-49 Democratic majority to 51-49 Republican majority.This represents the only time in U.S. history that the president's party gained control of a chamber of Congress in a mid-term election.During the 2002 House elections, all 435 seats in the House of Representatives plus five of the six non-voting Delegates from non-state districts were up for election that year.