proponent; person who proposes
Refers to a person who formally puts forward a plan, idea, or motion, often in business, legal, or organizational contexts.
He is the proponent of the new project.
Let's decide after hearing the proposer's opinion.
発案者 emphasizes the originator or initiator of an idea, while 提案者 focuses on the act of formally proposing it.
Compound of 提案 (proposal) + 者 (person). The reading is standard on'yomi.