Arthur Finkelstein, a reclusive political Svengali who revolutionized campaign polling and financing and helped elect a bevy of conservative candidates, including President Ronald Reagan and Prime Minister Benjamin Netanyahu of Israel, died on Friday August 18 2017 night in Ipswich, Mass., where he lived. He was 72. Mr. Finkelstein was among the first political strategists in the late 1970s to grasp the potential of a United States Supreme Court ruling that allowed putatively independent political committees to spend money on behalf of individual candidates and causes. The decision led to a proliferation of fund-raising vehicles that were supposed to be beyond the control of candidates or party officials but that in fact often worked in concert with their campaigns. One such group, the muscular National Conservative Political Action Committee, was established with Mr. Finkelstein’s help. As a gay, Jewish libertarian, Mr. Finkelstein helped elect homophobic candidates, once polled South Carolinians on whether they would support a rival candidate identified as a Jewish immigrant, and supported gay rights and abortion rights as what the political consultant Roger Stone, another of his protégés, called, in a phone interview, “a situational conservative.” Arthur Jay Finkelstein was born on May 18, 1945, in the East New York section of Brooklyn, the son of Jewish immigrants from Eastern Europe. His father, Morris, was a cabby. His mother was the former Zella Ordanksi. The family moved to Levittown, on Long Island, when he was 11, then to Queens, where he graduated from Forest Hills High School. In 1967, Mr. Finkelstein earned a bachelor’s degree in economics and political science from Queens College. As a student, he sometimes shared a college radio program with Ayn Rand, the author and philosopher whose laissez-faire capitalism he would fiercely defend in street-corner debates in Greenwich Village. F. Clifton White, the architect of the Draft Goldwater movement, became his patron and recruited him to James Buckley’s Senate race in 1970 as the candidate of the fledgling Conservative Party. In 1972, Mr. Finkelstein founded the Westchester County-based Arthur J. Finkelstein & Associates with his brother Ronald. Mr. Finkelstein was openly gay, although his sexual orientation was not common knowledge until it became the subject of an article in Boston Magazine in 1996. He married Donald Curiale, his partner of more than 50 years, in a civil ceremony in 2004. His survivors include Mr. Curiale; their daughters, Jennifer Elizabeth Delgado and Molly Julia Baird-Kelly; a granddaughter; and his brothers, Ronald and Barry.