We show that US politicians’ campaign advertisements between 2000 and 2020 are dominated by economic issues such as jobs and taxes, and rarely mention divisive cultural topics such as immigration, abortion, and guns. In contrast, we find that cultural topics dominate political news coverage, particularly cable news. Politicians underperform electorally when they emphasize cultural rather than economic issues, whereas news outlets attract larger audiences when they cover cultural rather than economic topics. We explain these differences in part through a difference in objectives: politicians maximize their vote share, whereas news outlets maximize their audience size. Linking campaign ads with individual voting decisions and high-frequency variation in TV news content with household-level viewership responses, we show that economic content is better for share-maximization and cultural content is better for size-maximization: economic content disproportionately attracts swing voters or swing viewers who would otherwise choose a politician’s or news outlet’s competitor, while cultural content disproportionately mobilizes individuals who would otherwise not vote or not view news. The media’s cultural focus spills over into politics: voters in constituencies exogenously more exposed to cable news weight cultural issues more heavily, and local politicians supply more cultural ads. Estimating a model of political competition and media choice, we show that the entry of cable news channels in the 1990s can explain 40% of the subsequent increase in cultural polarization.