In U.S. politics an Independent Democrat is an individual who loosely identifies with the ideals of the Democratic Party but chooses not to be a formal member of the party (chooses to be an independent). Independent Democrat is not a political party. Several elected officials, including members of Congress, have identified as Independent Democrats.
The first member of the United States House of Representatives to identify as an Independent Democrat was Zadok Casey of Illinois, who served from 1833 to 1843. Casey was a Jacksonian Democrat before becoming an Independent.
In 1848, a candidate for Mayor of Chicago, James Hutchinson Woodworth, labelled himself an Independent Democrat to distance himself from what was at the time a corrupt and disorganized Chicago Democratic party organization; he preferred being described as an Independent Democrat rather than as a Whig as that party was itself experiencing a transition. He won election in his first campaign by an overwhelming majority and then was re-elected for a second term. However his Mayoral political success sealed his departure from any further association with the then Illinois Democratic party. When the Whigs in Illinois became the new Republican party, and he was able to confirm that his Abolitionist ideals would be recognized, he registered as a member of the GOP. He subsequently was elected to the United States House of Representatives from Illinois as a member of the GOP. Woodworth served one term in Congress, and return to a banking career in Chicago that spanned the Civil War era and the Reconstruction.
Strom Thurmond of South Carolina was elected to the United States Senate in 1954 and served as an Independent Democrat in the 84th Congress until his resignation on April 4, 1956. In November of that year he was elected as a Democrat to fill the vacancy created by his resignation. Thurmond later became a member of the Republican Party in 1964.
In the 2006 primary, Joseph Lieberman of Connecticut, a Democratic incumbent U.S. Senator, lost the Democratic nomination for that office to entrepreneur Ned Lamont by a 52% to 48% margin. Lieberman created a new party called the Connecticut for Lieberman Party, obtained its nomination for the seat on the basis of signed petitions, and ran in the general election in November as its candidate--one of five on the ballot in that race. He won with 49.7% of the votes cast for the office. He had stated while campaigning that if elected he would to meet in caucus with the Democrats in the 110th United States Congress, and within the week following the election, he stated that he was "an Independent Democrat, capital I, capital D", and that he had specified as much to the secretary of the Senate. Throughout that Congress, he continued in that caucus (and it remained the majority caucus, with 51 or 50 members, complemented by the 49 or 48 Republicans caucusing together). As of December 2009 , during the 111th Congress, Lieberman was annotated as "ID-CT" on the U.S. Senate's "contact information" web page for him, and with "Independent" in the "Party" column (for both the 110th and 111th Congresses) on Congress's "Biographical Directory of the U.S. Congress" page for him.
Four members of the New York State Senate, Jeffrey Klein, Diane Savino, David Valesky, and David Carlucci, indicated they would form a similarly designated caucus separate from the Democratic conference in 2011, known as the Independent Democratic Conference. Following the 2009 New York State Senate Leadership Crisis the IDC formed a coalition government with then New York Senate Republican leader Dean Skelos to give Republicans control of the New York State Senate. In April 2018 the IDC announced they would dissolve and following the primary defeat of six of the eight members in the 2018 election the chamber returned to Democratic control in 2019.