An "outspoken supporter" refers to someone who openly and assertively expresses their strong support or advocacy for a particular cause, person, or idea. Full definition
Adam is one of the most outspoken supporters of solar energy technology in the Southern Tier and New York State. (southerntiersolarworks.org)
Kenneth Moales Jr. has been one of the most outspoken supporters of Governor Malloy's Corporate Education Reform Industry initiatives. (jonathanpelto.com)
All of that aside, Ayre is also a very outspoken supporter of Bitcoin Cash. (bitcoinnews.international)