the.com/proponent

Someone who believes in your idea enough to defend it at a dinner party.

means A person who actively supports or argues in favor of a plan, cause, or idea.

from From Latin proponere — 'to put forward' or 'to propose,' built from pro- ('forward') and ponere ('to put, place'). A proponent is literally one who puts the thing forward, holding it up for others to see — the same root that gave us 'propose' and 'proposition.'

vs advocate
advocate pleads, proponent just agrees loudly
root
latin proponere, to put forward
usage tell
often precedes of, rarely precedes action
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