Connecticut's major political groups during the first half of the 19th century were successively the Federalist Party, the Democratic-Republican coalition, the Democrats, and the Whigs. The political scene also included a number of minor political parties—the Anti-Masonic, Free Soil, Temperance, and Native American (Know-Nothing) parties—of which the Know-Nothings were the most successful, holding the governorship from 1855 to 1857. The Whig Party collapsed during the controversy over slavery in the 1850s, when the Republican Party emerged as the principal opposition to the Democrats.
From the 1850s to the present, the Democratic and Republican parties have dominated Connecticut politics. The Republicans held power in most of the years between the Civil War and the 1920s. Republican hegemony ended in 1930, when the Democrats elected Wilbur L. Cross as governor. Cross greatly strengthened the Connecticut Democratic Party by supporting organized labor and providing social legislation for the aged and the needy. The success of the increasingly liberal Democrats in the 1930s prodded Connecticut Republicans to become more forward-looking, and the two parties were fairly evenly matched between 1938 and 1954. Connecticut's Democrats have held power in most years since the mid-1950s.
Republican presidential candidates carried Connecticut for five successive elections starting in 1972 and ending with the victory of Democrat Bill Clinton in 1992. In the 1996 election, Clinton again carried the state. In the 2000 presidential election, Democrat Al Gore took the state with 56% of the vote to Republican George W. Bush's 39%. Green Party candidate Ralph Nader won 4% of the vote. In 2002 there were 1,847,247 registered voters; 36% were Democratic, 24% Republican, and 40% unaffiliated or members of other parties in 1998. The state had eight electoral votes in the 2000 presidential election.
In 2003 Democrats controlled the state senate, 21–15, and formed a majority in the state house (94 Democrats to 57 Republicans). Following the 2002 elections, Connecticut's delegation of US Representatives consisted of two Democrats and three Republicans (Connecticut lost a congressional seat in 2002). Both of Connecticut's US senators are Democrats: Christopher Dodd, reelected in l998 for his fourth consecutive term; and Joseph Lieberman, elected to his third term in 2000. Democratic presidential candidate Al Gore chose Lieberman as his running mate in the 2000 presidential election. In 2003, Connecticut ranked eighth among the 50 states in the percentage of women state legislators, at 29.4%.
In 1994 Republican John G. Rowland was elected governor on a platform that included a promise to repeal the state income tax; he was reelected in 1998 and 2002. US Representative Gary Franks, the first black member of the US House of Representatives from Connecticut and the first black House Republican in 55 years, was unseated in 1996, in his bid for a fourth term. In 1998 he made an unsuccessful run for US Senate, against incumbent (Democrat) Christopher Dodd.