This article demonstrates how the party identification of various demographic groups in California and Texas changed in response to the gubernatorial campaigns of Pete Wilson and George W. Bush. Using aggregated time series of Field Poll, Texas Poll, and Gallup data, difference-in-differences results show that Wilson’s embrace of Proposition 187 was followed by significant Hispanic movement toward the Democratic Party in California. Time series analysis substantiates that this action led to a long-term 7.1 percentage point Democratic shift among California’s Hispanics. This suggests that state-level actors can influence partisan coalitions in their state, beyond what would be expected from national-level factors.