 In 1968 he ran for Congress, but lost the Republican nomination to Whitney North Seymour Jr., who went on to be defeated by Democrat Ed Koch., Afterwards he was the New York City director of the United States Department of Housing and Urban Development.Green was elected as a Republican to the 95th United States Congress, to fill the vacancy caused by the resignation of Ed Koch, and was re-elected to the 96th, 97th, 98th, 99th, 100th, 101st and 102nd United States Congresses, holding office from February 14, 1978, to January 3, 1993.A mostly liberal Republican, he was one of the few members of his party to have a long run in office from a city long dominated by Democrats.