This paper considers how enlargement may affect the EU-UK relationship. Commission President Ursula von der Leyen and other EU leaders refer to enlargement as a “geopolitical imperative”.1 In practice, however, EU enlargement – both to Ukraine and Moldova and to the countries of the Western Balkans – is at risk of stalling again. Many candidates face significant internal challenges in meeting the requirements of EU membership, especially in terms of fighting corruption and strengthening the rule of law.2 On the EU side, there is still substantial caution about enlargement, manifested for example in the notion that the EU must reform before it can enlarge. The challenges faced by many candidates, combined with scepticism on the EU side, mean that that there is a real risk that enlargement will stall. To avoid that, the EU is increasingly emphasising the notion of phased or staged enlargement. The idea is that candidate countries can be gradually integrated into different EU policy areas over time. The EU may also develop alternatives to fullyfledged membership, for example a status of associate member as an intermediate destination on the way to membership. That could have important implications for the way the EU deals with other neighbours, including the UK. The paper will first consider what phased enlargement means in practice and what an associate membership of the EU could look like, including how it might differ from existing EU models for dealing with close partners like Switzerland and Norway. Secondly, the paper will assess what the benefits of such a status would be for the EU and its members, and for the partner countries. Finally, the paper turns to the question of what such a model would mean for the EU-UK relationship.
