Most research on the observance of the European Union’s (EU) fundamental values as laid down in Article 2 of the Treaty on European Union (TEU) focuses on the instruments that the EU primary law provides for the supranational EU institutions to sanction and incentivise member states’ governments. As the vast majority of national parties are part of one of the currently twelve European political parties (EuPPs), these organisations could provide another avenue through which the European level can foster the compliance of member states with the EU’s fundamental values. This paper examines the extent to which EuPPs can exert control over their member parties to safeguard the EU’s fundamental values. On the basis of two case studies – which explore the relationship between the European People’s Party (EPP) and its Hungarian member party Fidesz, and the relationship between the Party of European Socialists (PES) and its Slovak member party SMER – the paper assesses the instruments available to EuPPs and puts forward recommendations to improve the situation.