supporter, protagonist, champion, admirer, booster, friend
Meaning: a person who backs a politician or a team etc.; "all their supporters came out for the game"; "they are friends of the library"
He becomes Rockland's ardent supporter, and his purse is open and his influence is used to the fullest extent.
So far from rendering himself indispensable to Maud by constant little attentions, Reggie, to the disgust of his backer and supporter, seemed to spend most of his time with Alice Faraday.
Nevertheless, Mr. Cyrus Edwards boldly made his canvass for Governor as a supporter of the system of internal improvements, and his opponent, Thomas Carlin, was careful not to commit himself strongly on the other side.