Conventional wisdom suggests that partisanship is the "unmoved mover" in the minds of American voters. Revisionist theories hold that party updating is conditional on individual/contextual factors. By delimiting the scope conditions of the Michigan model, revisionist models do not fundamentally challenge the classic view. This paper proffers an unconditional model of party revision. We theorize that beliefs about government activism—operational ideology—are widely available and heuristically efficacious, and easily map onto party labels. Hence, operational ideology should drive party updating. Using data from seven panel studies covering 1990–2012, we demonstrate that (1) party shapes operational ideology, (2) operational ideology shapes party, (3) the ideology-to-party effects are as large as the party-to-ideology effects, and (4) neither sophistication nor education or elite polarization condition these relationships. These results push the revisionist model of party farther than it has gone before and suggest that operational ideology is a core predisposition in mass belief systems.