In a hyper-globalized world where competing forms of liberal and illiberal internationalisms are pronounced through protest movements, what role do domestic politics play in shaping these currents of international politics? How do domestic divides shape willingness towards international-oriented protest, where individuals protest on behalf of populations or policies occurring abroad? Focusing on the US, I theorize two partisan pathways that lead to international protest participation: Democrats may perceive efficacy and domestic consequences and Republicans may perceive organizational ties and ‘outwards influence’ as key motivations. Overall, I argue Democrats are more willing to participate in an international protest relative to Republicans. Utilizing abortion-rights as a case study and not taking for granted the assumed overlap between issue-partisanship, I also theorize that pro-life Democrats are most likely to participate in an international oriented protest due to a combination of protest efficacy and religious organizational ties.

I field a US online survey and find support for the theorized correlations and mechanisms. Democrats are particularly willing to protest for an international abortion issue, especially if they identify as pro-life, due to aligning with Democrats on the protest's efficacy, while being socio-organizationally aligned with Republicans on how the international is perceived. Commonalities with both parties mean that pro-life Democrats have a winning motivational cocktail for international-oriented protest. Such findings have implications for understanding protest behaviour for other issues cutting across partisan lines, complicates conventional perceptions of liberal protest being more internationally oriented, and demonstrate the domestic foundations of liberal and illiberal forms of international solidarity.