A growing body of research shows that incumbents employ heterogenous strategies in advancing energy transitions. We analyze how shifts in the policy positions of European power producers relate to technological changes on the firm level. We find that substitution of fossil-fuel assets with hydropower and nuclear, or new renewable energy (NRE) assets is strongly associated with cessation of opposition and the emergence of partial and strong support for more ambitious policies. However, utilities with notable new investment in NRE, but a dominant share of incumbent hydropower or nuclear in their portfolios, have not become more supportive of more ambitious renewable energy policies. We argue that substantial substitution is needed to re-make vested interests and engender more broad-based business support for accelerating the energy transition. Co-option by incumbents suggests that NRE is beyond the stage of niche technology, and that change may increasingly come from within the existing socio-technical regime.