Across the world, women continue to be underrepresented in parliaments. As gatekeepers to candidate lists, party leaders are in a pivotal position to promote gender balance. But do party elites consider women’s underrepresentation when deciding who to nominate? Leveraging a large-scale conjoint experiment with 1,389 party elites in Austria, Germany, and Switzerland, we find that the more underrepresented women are in candidate lists, the better the chances of women aspirants. Awareness of women’s underrepresentation influences selectors for whom promoting gender equality may be a less crystallized priority: centrists and men. Women’s underrepresentation also reinforces preferences for women aspirants among those for whom gender equality may be a core value (left-wing and women selectors) but does not affect those for whom opposing gender equality may bring electoral advantages (right-wing party elites). Our findings shed light on the potential role that signalling underrepresentation may have on party elites’ selection of women aspirants.