In parliamentary democracies, party primaries are increasingly used to select party leaders and electoral candidates. However, the factors influencing a candidate's success in these elections remain under-researched. This paper explores the extent to which primary voters support candidates endorsed by party elites by examining the electoral consequences of such endorsements. Drawing inspiration from US-based literature, it is proposed that party elites in parliamentary democracies, like members of parliament, can influence primary election outcomes through two distinct campaigning mechanisms. Firstly, party elites can directly campaign for a candidate in front of primary voters. Alternatively, they can support a candidate by mobilizing more voters to participate in the polls. To analyze the electoral impact of elite endorsements, this study examines three nationwide primaries from Spain's two main political parties since 2014: the conservative PP and the social democratic PSOE. Initial findings suggest that candidates endorsed by party elites tend to perform better, primarily due to higher voter turnout in areas where party elites actively support them.
