Nassau County Executive Thomas Suozzi conceded electoral defeat to his Republican challenger Legis. Edward Mangano Tuesday afternoon in a televised news conference from the ceremonial chamber of the Theodore Roosevelt Executive and Legislative Building in Mineola. Some political observers called it a stunning setback for an articulate, aggressive politician who has had ambitions for higher office.In another development, Democratic incumbent Comptroller Howard Weitzman also conceded defeat Tuesday to Republican challenger George Maragos. In a written statement Weitzman said: "I would like to congratulate George Maragos on his election as Nassau County comptroller. Although the results of the election are not what I hoped for, it has been an honor to serve the people of Nassau County for eight years and I am proud of what I have accomplished as comptroller."