A person who seeks office by election.  From Latin candidus meaning bright, clear, clean, or spotless

Roman togas were white.  Romans hoping to win elections wore extra white togas.  The candidate would add chalk power to his toga to further whiten things up.  This toga was the toga candida.  

Over time, Romans associated the toga with the person seeking office, the candidate.  The word stuck.  These days candidates do not wear togas on the campaign trail.  They just make sure their shirts are clean.  

A fool and his money are soon elected.  – Will Rogers