The answer to the crossword question ‘Rep.s opponent is DEM‘ is ‘Democrat‘. A ‘Rep.‘ is an abbreviation for a Republican, which is a member of the Republican Party in the United States. A ‘DEM‘ is an abbreviation for a Democrat, which is a member of the Democratic Party in the United States. Therefore, if a Rep. is running for election, their opponent would likely be a Democrat. This type of question is commonly found in political-themed crossword puzzles or puzzles with a theme related to political parties.