Millions of California voters regularly turn out in November but abstain from primary elections.A randomized Get Out the Vote experiment conducted in the state’s 2014 primary contestshows that this dormant electorate can be mobilized if campaigns target these unlikely voters.Here, we extend these findings to examine whether the electoral context of the district shapes theeffectiveness of a primary mobilization effort. To do so, we develop two conceptualizations ofcampaign context. The first is based on a district’s typical level of competitiveness. The secondlooks at total spending levels in the current campaign. Theories of voter information processingpredict differential responsiveness by voters to mobilization efforts in these different contexts.To test these predictions, we analyze a field experiment that sends direct mail to 149,596 registeredlow-propensity California voters. Consistent with theory, we find that voter mobilizationmailings have different effects in these two distinct contexts. Although mobilization efforts alwaysincrease turnout, in districts that are typically competitive we find that mobilization effortsare more effective. In contrast, in districts that saw large amounts of spending in the 2014 race,the same treatments are less effective. This suggests that a campaign looking for the largest marginalreturn should target races that have been competitive in prior races but that are receivinglittle attention in the present contest.
