Do two-party systems hamper defection from undemocratic candidates?

Do the electoral constraints imposed by two-party systems make citizens less likely to defect from undemocratic candidates? I employ two innovative candidate choice experiments fielded in England to answer this question. Specifically, I implement two designs manipulating the number and effective number of parties displayed between two and three, exploiting England’s party system characteristics. Contrary to expectations, I find that Labour and Conservative identifiers do not defect more from undemocratic in-partisan candidates when they face three (effective) parties–Labour, the Conservatives, and the Liberal Democrats–rather than just the two major parties. Instead, defection from undemocratic in-partisans to the out-party drops and relocates to the Liberal Democrats, even when the latter have no chance of winning. These findings highlight that having three parties does not generate more defection from undemocratic politicians and, consequently, does not reduce risks of democratic backsliding through this mechanism.