espouser

a person who actively supports or favors a cause became an espouser of environmental causes only after she decided to run for office Synonyms advocate, advocator, apostle, backer, booster, champion, expounder, exponent, friend, gospeler (or gospeller), herald, hierophant, high priest, paladin, promoter, proponent, protagonist, supporter, true believer, tub-thumper, white knightRelated Words loyalist, partisan (also partizan), stalwart; adherent, cohort, disciple, follower; interpreter; applauder, cheerleader, encourager, fellow travelerNear Antonyms enemy, foe, rival; belittler, critic, faultfinderAntonyms adversary, antagonist, opponent