John Moran Bailey (November 23, 1904 – April 10, 1975) was an American politician who played a major role in promoting the New Deal coalition of the Democratic Party and its liberal policy positions.

Bailey dominated Connecticut Democratic politics as a party chairman, from 1946 to his death in 1975. He typically had a decisive voice in selecting the party's candidates for top offices and in coordinating Democrats in the state legislature. He was even more powerful as the chairman of the Democratic National Committee from 1961 until 1968 and was one of the main behind-the-scenes backers of John F. Kennedy.

An Irish Catholic, Bailey was educated at The Catholic University of America and Harvard Law School.

John M Bailey, was one of the proud founders of the Young Democrats of America, serving as a national officer in 1935 from Connecticut, an organization which was crafted from the Presidential Candidacy of Franklin Delano Roosevelt in 1933.

Bailey was the dominant figure in Connecticut politics between 1950 and his death in 1975. From his office in Hartford two blocks from the State Capitol, he coordinated and controlled statewide election campaigns and the activities of the Connecticut General Assembly.

Bailey's tenure as head of the Connecticut Democratic party was credited with turning the state from one politically dominated by WASP Yankee Republicans to one dominated by Democratic candidates of Roman Catholic and Jewish background, such as Abraham Ribicoff, Thomas Dodd, John Dempsey, and Ella T. Grasso.

His Republican rival was Meade Alcorn, who also happened to serve as national chairman of his party.

Prior to his statewide activities, Bailey had served in local roles in his home city of Hartford.