Green was New York City Consumer Affairs Commissioner from 1990 to 1993 and was elected New York City Public Advocate in 1993 and 1997. He won Democratic primaries for the U.S. House of Representatives, U.S. Senate, and mayor of New York City, in each case losing the general election. Additionally, he has lost campaigns to be the Democratic nominee for U.S. Senate, the Democratic nominee for New York Attorney General, and the Democratic nominee for New York Public Advocate eight years after two terms in that position.