In politics one afflicted with self-respect and addicted to the vice of independence. A term of contempt.

A bolter from the Republican party in the national election of 1884; an Independent.

A person who is undecided about an issue, especially a political one; a person who takes a neutral stance on an issue; a fence-sitter.

someone who bolted from the Republican Party during the U.S. presidential election of 1884

a neutral or uncommitted person (especially in politics)

a fence-sitter -- i

a politician who refuses to follow the directives of a particular political party

The Mugwumps were a political movement comprising Republicans who supported Democratic candidate Grover Cleveland in the United States presidential election of 1884. They switched parties because they could not in good faith support the Republican candidate, James Blaine of Maine. After the election was over, mugwump survived for more than a decade as an epithet in American politics, and the Mugwumps themselves continued many of their associations as reformers well into the 20th century.