rail-splitter
/ˈreɪlˌsplɪtə/Chiefly US
noun
A person who splits wood for rails, especially for use in fencing. Frequently in the (great,also old) rail-splitter: Abraham Lincoln. Hence: = republican.
Origin
Mid 19th century; earliest use found in William Simms (1806–1870), poet, novelist, and historian. From rail + splitter.