Mugwump
The Mugwumps were Republican political activists who bolted from the United States Republican Party by supporting Democratic candidate Grover Cleveland in the United States presidential election of 1884. They switched parties because they rejected the financial corruption associated with Republican candidate James G. Blaine. In a close election, the Mugwumps supposedly made the difference in New York state and swung the election to Cleveland. The jocular word mugwump, noted as early as 1832, is from Algonquian (Natick) mugquomp, "important person, kingpin" (from mugumquomp, "war leader") implying that they were "sanctimonious" or "holier-than-thou," in holding themselves aloof from party politics.
Read more about Mugwump.