Democratic backsliding in European Union (EU) member states is not only a policy challenge for the EU, but also a potential existential crisis. If the EU does too little to deal with member state regimes that go back on their commitments to democracy and the rule of law, this risks undermining the EU from within. On the other hand, if the EU takes drastic action, this might split the EU. This article explores the nature and dynamics of democratic backsliding in EU member states, and analyses the EU’s capacity, policy tools and political will to address the challenge. Empirically it draws on the cases that have promoted serious criticism from the Commission and the European Parliament: Hungary, Poland, and to a lesser extent, Romania. After reviewing the literature and defining backsliding as a gradual, deliberate, but open-ended process of de-democratization, the article analyzes the dynamics of backsliding and the EU’s difficulties in dealing with this challenge to liberal democracy and the rule of law. The Hungarian and Polish populist right’s “illiberal” projects involve centralization of power in the hands of the executive and the party, and limiting the independence of the judiciary, the media and civil society. This has brought both governments into direct confrontation with the European Commission. However, the EU’s track record in managing backsliding crises is at best mixed. This comes down to a combination of limited tools and lack of political will. Ordinary infringement procedures offer a limited toolbox, and the Commission has proven reluctant to use even these tools fully. At the same time, party groups in the European Parliament and many member state governments have been reluctant to criticize one of their own, let alone go down the path of suspending aspect of a states’ EU membership. Hence the EU’s dilemma: it is caught between undermining its own values and cohesion through inaction on one hand, and relegating one or more member states it to a second tier—or even pushing them out altogether—on the other.