In most democracies, members of parliament tend to be better off than the citizens they are elected to represent. How can we explain why democratic parliaments are systematically run by the affluent? Previous research has mostly focused on the explanation that voters may prefer to elect candidates who are better off than they themselves are. The goal of this paper is to explore an alternative mechanism, viz., whether political parties favor well-off rather than less well-off candidates. To examine this question, I analyze data from the 2007 election to the lower chamber of the Swiss parliament. The results show that parties are more likely to assign favorable party list positions to candidates who are fairly well-off. In particular, I find that parties favor candidates from the skilled working class or the core middle class over candidates from the routine working class as well as candidates who are well educated over candidates who are less well educated. These findings suggest that party bias in the candidate nomination process is a factor contributing to the descriptive misrepresentation by income and social class that is so common in current democracies.