a
person who advocates a theory, proposal, or project.
synonyms:
advocate · supporter · upholder · exponent · promoter · adherent · endorser ·
champion · defender · backer · subscriber · patron · espouser ·
friend · apostle · apologist
Donald
J. Trump is a proponent of a wall along the southern U.
S.A. / Mexico border.
Our president is a supporter/endorser/defender/
champion/backer of a wall along the southern U.S.A. / Mexico border..