Very happy to see my paper “How substitutable are the classical and radical right?” with Carlos Sanz (at the Banco de España and CEMFI) published in the Journal of Public Economics. The paper addresses a simple question: take a party of the classical right (e.g., CDU in Germany or PP in Spain) and a party of the radical right (e.g., AfD in Germany or Vox in Spain). Are these parties substitutes (i.e., voters think they are two slightly different flavors of the same political platform) or complements (i.e., voters think each party is sufficiently different from the other)? Note that the question is not whether the parties differ under an objective metric, but what the voters think. The challenge is that using polls or surveys is difficult: voters of radical-right parties are reluctant to disclose their positions to pollsters. Repeated polling mistakes underestimating Trump’s support from 2016 to 2024 illustrate this point. So, we take advantage of a quasi-natural experiment in Spain during the high-stakes July 23, 2023 general election. Vox, the radical party, failed to field candidates in one parliamentary constituency, Santa Cruz de Tenerife (Tenerife for short), due to a last-minute infight within the party over the positions on the list (Spain uses PR for its parliament's lower house). So, while Vox ran in all the other 51 constituencies, it could not run in Tenerife. This was a genuine surprise for everyone involved, including Vox’s national direction and all the other parties that had filed candidates in Tenerife, who had assumed Vox would run. As luck has it, Tenerife is close to being quite representative of elections in Spain: it elects seven members of the lower house under PR (so the scope for strategic voting is quite limited), it is not too left- or too right-wing leaning, and it has a moderate presence of a territorial party, as many other constituencies in Spain. Its demographics and socioeconomic conditions are also reasonably close to the median, and Vox’s local power infight was unrelated to any relevant variable that might have affected electoral outcomes. We estimate the effects of Vox’s absence on electoral outcomes using a synthetic difference-in-differences model that controls as best as possible for all remaining differences between Tenerife and other constituencies. Our main finding is that 82.9% of Vox’s voters in Tenerife switched to PP. So, yes, for a very large majority of voters, PP is a substitute (perhaps imperfect) of Vox. But, interestingly, it is not for 17.1% of voters, who either abstained or moved to other parties. Moreover, this percentage of Vox’s voters not moving to PP is higher in precincts with low education, low income, and higher unemployment. For voters in less-favored precincts, Vox and PP are clearly two distinct political platforms. Why is this so important? Because it shows that the total share of votes of the right increases when there are two right-wing parties on the ballot, a classical and a radical one, as they cater to similar but not fully overlapping demographics. The PP leadership and many media commentators in Spain have repeatedly argued since 2023 that the PP’s failure to gain a parliamentary majority in the 2023 general election was due to Vox's presence. We argue that, given our estimates, there is no evidence of that. If we extrapolate the results in Tenerife to the rest of Spain (i.e., a counterfactual election without Vox), the PP would have still failed to gain a majority. Of course, the paper has many more details (including tons of validation analyses and caveats about the possible limitations of our econometric exercise), so I invite you to read them. Even more material did not come out of the cut room. Carlos and I could have written a whole monograph on this topic. For example, we have some suggestive evidence that this phenomenon of widening of the right share of the vote when a (electorally viable) radical-right party is on the ballot is present across all of Europe Finally, a great thanks to the editor, @pereztruglia, who did a fantastic job, and the referees. Sometimes, papers do not improve much in the peer-review process. This time, it certainly did.