Campaign language in the United States has grown markedly polarized, with candidates increasingly speaking in party-distinctive ways. Yet the mechanisms driving this linguistic divergence remain insufficiently understood. This study proposes identity–policy fusion, a framing strategy in which candidates embed distinctive biographical vocabulary into policy statements, as one factor shaping this divergence. By framing policy as an authentic extension of lived experience, fusion may tie stances to in-group identity and biographical authority, raising the psychological and social costs of disagreement. Using computational text analysis of 41,842 policy statements from 3,343 U.S. House candidates in the 2018, 2020, and 2022 election cycles, the study operationalizes fusion as term frequency–inverse document frequency (TF–IDF)-weighted lexical overlap between biographies and policy texts, and polarization as a statement’s relative similarity to in-party versus out-party linguistic norms within policy domains. Ordinary least squares regression shows that fusion is significantly associated with higher polarization in campaign language, with the association approximately 26 percent stronger for Republicans than Democrats. This partisan asymmetry is consistent with fusion serving as an alternative source of legitimation under conditions of contested institutional authority, illuminating a potential mechanism through which elite messaging may harden partisan boundaries.