Previous research has demonstrated the relevance of voters' and candidates' group memberships on voting behavior. We examined the impact of voters' race (Black vs. White) and gender (male vs. female) on voting preferences for either Barack Obama or Hillary Clinton in the Democratic primaries and caucuses of 2008. Study 1 investigated national exit poll data, representative for voters from various U.S. states. Analyses revealed a same-race and same-gender voting preference. Confirming the threat hypothesis (Blalock, 1967), same-race preference among White voters (but not among Black voters) increased with the proportion of Blacks per state. In Study 2, we assessed voting preferences, racial identification, and perceived realistic threat by Blacks among White voters. High racial identification was associated with a stronger same-race preference. This effect was mediated by perceived realistic threat. We discuss the results with regard to the intergroup threat versus contact hypothesis, and psychological differences between racial majority and minority members.