How can women's representation improve in countries that do not embrace legislated gender quotas? We study municipal elections in Turkey during 2009-2019. A conservative dominant party, Erdogan's AKP, is often challenged by a Kurdish party that promotes gender equality in electoral lists. Exploiting within-municipality variation, we find that the Kurdish party winning leads AKP to increase its share of female candidates by 25 to 30% in the next election. Other opposition parties winning has a substantially lower impact. Our results suggest that one party empowering women can help reducing gender gaps in lists across-the-board.