Legitimize or Delegitimize? Mainstream Party Strategy toward (Former) Pariah Parties and How Voters Respond

Mainstream parties have often shifted from initially portraying new competitors as undemocratic pariahs (i.e., a delegitimizing strategy) to portraying the same parties later as democratic (i.e., a legitimizing strategy). I argue that voters follow mainstream parties’ legitimizing strategies in their legitimacy evaluations of these parties. I investigate this argument with two independent survey experiments and a quantitative media content analysis in two countries that differ sharply in the nature of party competition—from mainstream parties delegitimizing a far-right party (i.e., Germany) to mainstream parties legitimizing it (i.e., Sweden). I find strong evidence that (a) mainstream parties can effectively legitimize pariah parties in the eyes of voters, (b) turning back to delegitimization has little effect, (c) legitimization is no less effective in the face of a third party’s delegitimizing strategy, and (d) legitimization resonates beyond co-partisans. The results suggest that mainstream party legitimization of pariah parties has far-reaching consequences.