What is another word for "advocate"?

Roget's Thesaurus (1911) lists these synonyms for "advocate": abettor, accessory, accomplice, acquaintance, adherent, adjunct, adjutant, adjuvant, adviser, after, agent, all, ally, alter, ambassador, ambo, amigo, and, angel, arbitrator, assistant, associate, association, attache, attorney, auctioneer, auxiliary, backer, bagman, bailiff, banco, bar, barrister, beagle, bedfellow, bencher, best, boon, bosom, broker.