This article focuses on the role played by the Labour Party in two devolution referendums, in Wales in 1997 and in the North-East region in 2004. Comparing the positive vote of the Welsh and the negative vote of the North shows how the governing party -the Labour Party which has also been historically dominant in each of these regions -contributed to the contrasting outcome. Our argument is that dominant parties impact both in their formal (structural, institutional) and non-formal (cultural, identity) aspects. The crucial role of the leading party is thus to enable (or constrain) a sub-state space for politics and popular mobilisation on territorial grounds. system is led astray if the dominant party is incapable of reflecting that development in its own structures. Such capacity, we will claim, requires extensive efforts at both the regional and the central level.Through its comparative analysis the article seeks to demonstrate the important role of multi-level parties (MLP) in particular with regard to the successful prosecution of referendum campaigns. In making this case the purpose is not to argue that the intrainstitutional structures of the MLP are the only decisive factor in explaining the success or failure of campaigns for regional devolution, but rather to explicate the manner in which they affect the trajectory -and, in a broader perspective, the process of regionalisation.Studies from other European countries have shown that the dominant party may be decisive to the outcome of referendums when it comes to positioning, but even more so with regard to mobilising the vote.State and sub-state politics unfold within political systems that differ substantially in terms of institutional structures, policy programs, party systems, collective identities, and levers of political influence. Capturing the relationship between these different territorial levels is decisive to accounts of modern politics; furthermore, as political parties are normally operative at both state and sub-state levels (including separatist