Greater efforts are needed to bridge the emission gap between Nationally Determined Contributions and the objective to limit climate change below 2°C. This paper focuses on four European-Union countries: Germany, France, Poland and UK that represent on aggregate 55% of current EU emissions. It analyses national mitigation strategies produced by national research teams in the framework of the COP21_RIPPLES project and compatible with a long-term objective leading to a well below 2°C target either as part of an ambition in 2030 limited to that of the NDCs, or as part of more ambitious early action. We use the decarbonization wedges methodology, an advanced index decomposition analysis methodology for quantifying the contribution of different mitigation strategies. This makes it possible to assess the priorities for action to strengthen the NDCs. The article also highlights the impact sectoral growth dynamics have on the emission trajectories and the resulting necessary mitigation efforts.