 In 1859, he was nominated by Tammany Hall to run against Democratic candidate Fernando Wood, who had lost favor with some of the Tammany factions, and the Republican candidate George Opdyke.Havemeyer narrowly lost to Wood 30,000 to 27,000 (Opdyke gained 23,000 votes).During the American Civil War, Havemeyer was a strong advocate of the Union and urged the abolition of slavery as a war measure.