<p>Do party crises affect the cohesion of political parties’ networks in social media? Focussing on five major Spanish political parties, we analyse the changes in the following-follower and retweet networks during the period between 2021 and 2023 using a sample of 4110 Twitter accounts that includes different strata of the political parties, from elites and intermediate elites to the party on the ground and sympathisers. Our results suggest that network cohesion may weaken when political parties undergo intense crises. In particular, we find that the network of the party Ciudadanos (Cs), which suffered from a rapid electoral downfall, has lost followers amongst its own ranks and comparatively shows a less compact pattern of retweet activity. Remarkably, the erosion is more intense in peripheral segments of the online party, namely amongst sympathisers, who are more likely to distance themselves from the elite. Overall, we conclude that the evolution of the structure and composition of social media networks can be a useful indicator to identify problems of cohesion within political parties.</p>