To go on the stump
|to engage in making public addresses for electioneering purposes; - a phrase derived from the practice of using a stump for a speaker's platform in newly-settled districts. Hence also the phrases stump orator, stump speaker, stump speech, stump oratory, etc.|
See also: Stump
Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.