中文摘要
过去几十年间，民粹主义政党在欧洲政治中获得了显著权力，引发了对其可能产生传染效应的担忧。我研究民粹主义政党在地方议会中的代表席位如何影响其他政党的意识形态立场。我利用势均力敌的选举所产生的变异，来识别由政党代表席位变化所导致的意识形态转变，同时保持选民偏好不变。我使用来自投票建议应用程序的候选人层面数据来估计意识形态立场，采用项目反应理论对候选人的作答进行建模，从而获得在不同选举年份之间可比的意识形态测度。结果显示，民粹主义代表席位的增加，使该市镇其他政党候选人的意识形态谱系变得更加集中。民粹主义政党每增加一个席位，候选人立场的四分位距便缩小9%。尽管主流政党与民粹主义政党之间最初出现了意识形态趋同，但随着民粹主义政党继续获得更多席位，这一趋同并未持续。这些效应仅出现在自由—保守维度上，而经济维度上的立场则不受影响。结果表明，民粹主义代表席位的增加会影响其他政党，并导致候选人群体内部的意识形态趋同。
Abstract
Populist parties have gained significant power in European politics in the last decades, raising concerns about the potentially contagious effect of populism. I study how populist party representation in local councils affects other parties’ ideological positions. I use variation created by close elections to identify ideological shifts resulting from a change in party representation, holding voter preferences constant. I use candidate-level data from a voting advice application to estimate ideological positions, modeling candidates’ responses using item response theory to obtain measures of ideology that are comparable across election years. The results show that increased populist representation causes the ideological spectrum among other parties’ candidates in the municipality to become more concentrated. One additional seat for the populist party reduces the interquartile range of candidate positions by 9 %. While there is initial ideological convergence between mainstream and populist parties, it does not persist as the populist party continues to gain more seats. These effects take place only on the liberal-conservative dimension, while positions on the economic dimension are unaffected. The results demonstrate that increased populist representation influences other parties and causes ideological convergence within the candidate base.