In recent years interactive decision making has become quite popular in The Netherlands, especially at the level of local government. It involves new forms of participation of citizens, consumers of public services and interest groups in the process of policy formation. Workshops, panels, internet discussions and a lot of other techniques are used to arrive at innovative and supported solutions for existing problems. The ambitions are high: these new forms of participation should result in better government both in the sense of providing bettet policies , but also in bridging the democratic gap between local government and citizens. However, these new forms of participation in local government are not without problems. Recent experiences suggest that one of the major problems is the challenge interactive decision making constitutes for the existing practice of representative politics. On the basis of two cases - the decision-making process concerning the expansion of the Rotterdam region - this article illustrates that one of the barriers that stands in the way of the sucess of such processes is the ambiguous attitude of elected politicians. Although politicians often initiate interactive decision-making processes, they do not actively support these processes when they are in progress. The outcomes of interactive decision-making progress are often not used in the formal political procedures that follow. Because elected politicians fear that these formal political procedures threaten their political primacy, they find it hard to play a constructive role in these processes. In this pape we suggest that if politicians are serious about interactive decision making, they should reflect on their own roel in it. Building upon empirical insights of the cases and on a discussion of two possible approaches to democracy, we suggest alternative roles of politicians. The prevailing substantive definition of primacy of politics should be redefined in order to allow politicians to fulfil the role of catalyst and facilitator of the public debate. In this way the eroded role of politicians in societal decision making may gain a new meaning