John J. Sweeney, a New York union researcher who climbed to the pinnacle of the American labor movement in the 1990s, leading the A.F.L.-C.I.O. for 14 years through an era of fading union membership but rising political influence, died on Monday February 1 2021 at his home in Bethesda, Md. He was 86. Sweeney was elected president of the AFL-CIO at the federation's biennial convention in October 1995 and has been re-elected three times since then. At the time of his election, he was serving his fourth four-year term as president of SEIU, which grew from 625,000 to 1.1 million members under his leadership. An AFL-CIO vice president since 1980, Sweeney was born May 5, 1934, in Bronx, N.Y. He worked as a gravedigger and building porter (and joined his first union) to pay his way through Iona College, a Catholic school in New Rochelle, N.Y., where he earned a bachelor’s degree in economics in 1956. His trade union career began as a research assistant with the Ladies Garment Workers. In 1960, he joined SEIU as a contract director for New York City Local 32B. He went on to become union president and to lead two citywide strikes of apartment maintenance workers. In 1980, he was elected president of the international. In 1962, Mr. Sweeney married Maureen Power, a schoolteacher. She survives him, along with their children, John Jr. and Patricia Sweeney; two sisters, Cathy Hammill and Peggy King; and a granddaughter.