In addition to Mr. Green , a former public advocate of New York City , and Mr. Cuomo , a former federal housing secretary , the race has also attracted Assemblyman Richard L. Brodsky of Westchester County ; Sean P. Maloney , a former aide to President Bill Clinton ; Charlie King , the head of a nonprofit group that provides housing for the homeless ; and Denise O'Donnell , a former United States attorney for the Western District of New York .