Objectives Voters develop not only different opinions about politics but also different sets of empirical beliefs. It is less clear how falsifiable beliefs take hold. In particular, it remains unclear as to whether news and campaign messages, moderated by political knowledge, drive the process, or whether deep‐seated values principally sway voters' acceptance of factual claims. These contrasting views point to a set of testable hypotheses that we use to refine a model of ideologically‐biased empirical belief generation, which we call “knowledge distortion.”

Methods We conduct an analysis of survey data on three ballot measures in Washington State, testing hypothesized relationships between voters' empirical beliefs about political issues, news and campaign messages, political knowledge, political values, and partisanship, as well as vote choices on the ballot measures.

Results Our analysis reveals that voters' values and partisanship had the strongest associations with distorted beliefs, which then influenced voting choices. Self‐reported levels of exposure to media and campaign messages played a surprisingly limited role.