Sweeney, John Joseph, 1934–, U.S. labor leader, b. New York City. An official of the Service Employees International Union (SEIU) from 1960, he became president of the SEIU in 1980. As president, he emphasized organizing new workers and nearly doubled the union's membership. In 1995 he led dissatisfied labor leaders who challenged American Federation of Labor and Congress of Industrial Organizations president Lane Kirkland. After Kirkland resigned, Sweeney defeated Thomas Donahue, who had been appointed interim president, for the presidency of the AFL-CIO in the first contested such election in the organization's history. An unsuccessful challenge to his continued leadership resulted in 2005 in a split in the AFL-CIO, and several large unions with a total of more than 5 million members left the organization.
