Do external threats increase bipartisanship in the United States? An experimental test in the shadow of China's rise

Do external threats increase American bipartisanship? We subject this question to an experimental test. Leveraging the Biden and Trump administrations’ similar characterization of the China threat, we exposed American respondents to real-world primes about security threats from China, while randomizing the messenger of such primes. We find that the threat primes—regardless of the partisan identity of their messenger—boosted Democrats’ and Republicans’ support for assertive foreign policy in a largely parallel manner, thereby failing to reduce preference polarization. Importantly, there were no measurable changes across multiple indicators of affective polarization. These findings clarify the limits of external threats in uniting Americans, while also challenging recent perspectives that external threats—often colored by elite rhetoric—will further polarize the American public.