1) Adherent 2) Advocate 3) Advocator 4) An advocate 5) Exponent 6) Human 7) Individual 8) Mortal 9) Person 10) Somebody 11) Someone 12) Soul 1) Admirer 2) Advocate 3) Advocator 4) Apologist 5) Booster 6) Constitutionalist 7) Drumbeater 8) Exponent 9) Ideologist 10) Ideologue 11) Irredentist 12) Irridentist 13) Jansenist 14) Justifier 15) Neutralist 16) Nullifier 17) Partitionist 18) Platonist 19) Populist 20) Protagonist 21) Protectionist 
• (a.) Making proposals; proposing. • (n.) One who makes a proposal, or lays down a proposition. • (n.) The propounder of a thing.
Pro·po'nent adjective [ Latin proponens , present participle] Making proposals; proposing. 
a person who puts forward a proposition or proposal. · a person who argues in favor of something; an advocate. · a personwho supports a cause or doctrine; adherent. · a person who propounds a legal instrument, such as a will for probate.
a person who pleads for a cause or propounds an idea
a person who pleads for a cause or propounds an idea