Parties are the nucleus of modern parliaments. Therefore it is crucial to understand cooperation and competition within parties. In most parliaments, we can observe some form of cooperation, like cosponsorship. In this paper, cosponsorship is used to identify the relationships of MPs within their parliamentary party group, and to infer whether this relational position has an effect on their reselection. Are better embedded and connected MPs more likely to be reselected? Do peers matter in reselection? This question is also of theoretical interest in the light of competing principals (Carey, 2007). The empirical analysis first replicates the model of MP renomination by Baumann et al. (2017), adding a new data set from the German Bundestag, used to provide the relational independent variables of cosponsorship centrality. The key finding of the analysis is indeed: cosponsorship closeness is a significant predictor of MP reselection and can be seen as a compelling complement to the model by Baumann et al. With cooperation shown to be significant when it comes to renomination, the understanding of peer-induced competition, competing principals theory can be further developed, to aid our understanding of MP cooperation and competition, delegation, agency and collective principals in modern parties.