We empirically investigate key dynamic features of advertising competition in elections using a new dataset of very high-frequency, household-level television viewing matched to campaign advertising exposures. First, we show that exposure to campaign advertising increases households’ consumption of news programming by 3-4 minutes on average over the next 24 hours. The identification compares households viewing a program when a political ad appeared to viewers in the same market who barely missed it. Second, we show that these effects decline over the campaign. Together, these dynamic forces help rationalize why candidates deploy much of their advertising budgets well before election day.